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Interactions between Haloperidol and Unit-Hist Drops

2 drug interactions and 62 additional warnings found for the following 2 drugs:

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Drug interactions

Moderate drug interactions

Moderate:

haloperidol pseudoephedrine

Applies to: haloperidol and Unit-Hist Drops (brompheniramine / pseudoephedrine)
Generally avoid

Butyrophenone neuroleptics may antagonize the pharmacologic effects of amphetamine, amphetamine derivatives, and other centrally-acting sympathomimetic agents (i.e., CNS stimulants). Conversely, these agents may diminish the neuroleptic efficacy of butyrophenones. The exact mechanism of interaction is unknown but may involve opposing effects on dopaminergic activity. Several clinical studies have demonstrated the reduction or lack of effect of amphetamines on weight loss in obese psychiatric patients treated with haloperidol and other neuroleptic agents, most notably chlorpromazine. In one of these studies, dextroamphetamine also had no effect on sleep patterns. Another study found haloperidol to inhibit amphetamine-induced symptoms and may be useful in amphetamine intoxication. As for the reverse interaction, it is uncertain whether CNS stimulants actually antagonize the neuroleptic effect of butyrophenones, since CNS stimulants alone have been reported to cause or aggravate preexisting psychotic symptoms. There has also been a report of acute dystonia occurring in two normal, healthy young women given haloperidol and dexamphetamine as part of a neuropharmacological study. The authors postulated that the reaction was due to a potentiation of dopamine release.

Management

Amphetamine, amphetamine derivatives, and other CNS stimulants should generally not be used, particularly for weight reduction, in patients treated with a butyrophenone neuroleptic agent.

References (23)
  1. Reid AA (1964) "Pharmacological antagonism between chlorpromazine and phenmetrazine in mental hospital patients." Med J Aust, 1, p. 187-8
  2. Sletten IW, Ognjanov V, Menendez S, Sundland D, El-Toumi A (1967) "Weight reduction with chlorphentermine and phenmetrazine in obese psychiatric patients during chlorpromazine therapy." Curr Ther Res Clin Exp, 9, p. 570-5
  3. Casey JF, Hollister LE, Klett CJ, Lasky JJ, Caffey EM (1961) "Combined drug therapy of chronic schizophrenics." Am J Psychiatry, 177, p. 997
  4. Modell W, Hussar AE (1965) "Failure of dextroamphetamine sulfate to incluence eating and sleeping patterns in obese schizophrenic patients." JAMA, 193, p. 275-8
  5. Angrist B, Lee HK, Gershon S (1974) "The antagonism of amphetamine-induced symptomatology by a neuroleptic." Am J Psychiatry, 131, p. 817-9
  6. Cornelius JR, Soloff PH, Reynolds CF, 3d (1984) "Paranoia, homicidal behavior, and seizures associated with phenylpropanolamine." Am J Psychiatry, 141, p. 120-1
  7. Achor MB, Extein I (1981) "Diet aids, mania, and affective illness" Am J Psychiatry, 138, p. 392
  8. Schaffer CB, Pauli MW (1980) "Psychotic reaction caused by proprietary oral diet agents." Am J Psychiatry, 137, p. 1256-7
  9. Grieger TA, Clayton AH, Goyer PF (1990) "Affective disorder following use of phenylpropanolamine" Am J Psychiatry, 147, p. 367-8
  10. Dietz AJ, Jr (1981) "Amphetamine-like reactions to phenylpropanolamine." JAMA, 245, p. 601-2
  11. Norvenius G, Widerlov E, Lonnerholm G (1979) "Phenylpropanolamine and mental disturbances" Lancet, 2, p. 1367-8
  12. Mueller SM (1983) "Neurologic complications of phenylpropanolamine use." Neurology, 33, p. 650-2
  13. Lake CR, Tenglin R, Chernow B, Holloway HC (1983) "Psychomotor stimulant-induced mania in a genetically predisposed patient: a review of the literature and report of a case." J Clin Psychopharmacol, 3, p. 97-100
  14. Capstick C, Checkley S, Gray J, Dawe S (1994) "Dystonia induced by amphetamine and haloperidol." Br J Psychiatry, 165, p. 276
  15. Lake CR (1991) "Manic psychosis after coffee and phenylpropanolamine." Biol Psychiatry, 30, p. 401-4
  16. Lambert MT (1987) "Paranoid psychoses after abuse of proprietary cold remedies." Br J Psychiatry, 151:, p. 548-50
  17. Wharton BK (1970) "Nasal decongestants and paranoid psychosis." Br J Psychiatry, 117, p. 439-40
  18. Dewsnap P, Libby G (1992) "A case of affective psychosis after routine use of proprietary cold remedy containing phenylpropanolamine" Hum Exp Toxicol, 11, p. 295-6
  19. Finton CK, Barton M, Chernow B (1982) "Possible adverse effects of phenylpropanolamine (diet pills) on sympathetic nervous system function--caveat emptor!" Mil Med, 147, p. 1072
  20. Stroe AE, Hall J, Amin F (1995) "Psychotic episode related to phenylpropanolamine and amantadine in a healthy female." Gen Hosp Psychiatry, 17, p. 457-8
  21. Marshall RD, Douglas CJ (1994) "Phenylpropanolamine-induced psychosis: potential predisposing factors." Gen Hosp Psychiatry, 16, p. 358-60
  22. (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
  23. (2007) "Product Information. Vyvanse (lisdexamfetamine)." Shire US Inc
Moderate:

haloperidol brompheniramine

Applies to: haloperidol and Unit-Hist Drops (brompheniramine / pseudoephedrine)
Monitor

Agents with anticholinergic properties (e.g., sedating antihistamines; antispasmodics; neuroleptics; phenothiazines; skeletal muscle relaxants; tricyclic antidepressants; disopyramide) may have additive effects when used in combination. Excessive parasympatholytic effects may result in paralytic ileus, hyperthermia, heat stroke, and the anticholinergic intoxication syndrome. Peripheral symptoms of intoxication commonly include mydriasis, blurred vision, flushed face, fever, dry skin and mucous membranes, tachycardia, urinary retention, and constipation. Central symptoms may include memory loss, disorientation, incoherence, hallucinations, psychosis, delirium, hyperactivity, twitching or jerking movements, stereotypy, and seizures. Central nervous system-depressant effects may also be additively or synergistically increased when these agents are combined, especially in elderly or debilitated patients. Use of neuroleptics in combination with other neuroleptics or anticholinergic agents may increase the risk of tardive dyskinesia. In addition, some neuroleptics and tricyclic antidepressants may cause prolongation of the QT interval and theoretically, concurrent use of two or more drugs that can cause QT interval prolongation may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death.

Management

Caution is advised when agents with anticholinergic properties are combined, particularly in the elderly and those with underlying organic brain disease, who tend to be more sensitive to the central anticholinergic effects of these drugs and in whom toxicity symptoms may be easily overlooked. Patients should be advised to notify their physician promptly if they experience potential symptoms of anticholinergic intoxication such as abdominal pain, fever, heat intolerance, blurred vision, confusion, and/or hallucinations. Ambulatory patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them. A reduction in anticholinergic dosages may be necessary if excessive adverse effects develop.

References (15)
  1. Stadnyk AN, Glezos JD (1983) "Drug-induced heat stroke." Can Med Assoc J, 128, p. 957-9
  2. Zelman S, Guillan R (1970) "Heat stroke in phenothiazine-treated patients: a report of three fatalities." Am J Psychiatry, 126, p. 1787-90
  3. Mann SC, Boger WP (1978) "Psychotropic drugs, summer heat and humidity, and hyperplexia: a danger restated." Am J Psychiatry, 135, p. 1097-100
  4. Warnes H, Lehmann HE, Ban TA (1967) "Adynamic ileus during psychoactive medication: a report of three fatal and five severe cases." Can Med Assoc J, 96, p. 1112-3
  5. Gershon S, Neubauer H, Sundland DM (1965) "Interaction between some anticholinergic agents and phenothiazines." Clin Pharmacol Ther, 6, p. 749-56
  6. Sarnquist F, Larson CP Jr (1973) "Drug-induced heat stroke." Anesthesiology, 39, p. 348-50
  7. Johnson AL, Hollister LE, Berger PA (1981) "The anticholinergic intoxication syndrome: diagnosis and treatment." J Clin Psychiatry, 42, p. 313-7
  8. Lee BS (1986) "Possibility of hyperpyrexia with antipsychotic and anticholinergic drugs." J Clin Psychiatry, 47, p. 571
  9. Forester D (1978) "Fatal drug-induced heat stroke." JACEP, 7, p. 243-4
  10. Moreau A, Jones BD, Banno V (1986) "Chronic central anticholinergic toxicity in manic depressive illness mimicking dementia." Can J Psychiatry, 31, p. 339-41
  11. Hvizdos AJ, Bennett JA, Wells BG, Rappaport KB, Mendel SA (1983) "Anticholinergic psychosis in a patient receiving usual doses of haloperidol." Clin Pharm, 2, p. 174-8
  12. Cohen MA, Alfonso CA, Mosquera M (1994) "Development of urinary retention during treatment with clozapine and meclizine [published erratum appears in Am J Psychiatry 1994 Jun;151(6):952]." Am J Psychiatry, 151, p. 619-20
  13. (2001) "Product Information. Cogentin (benztropine)." Merck & Co., Inc
  14. Kulik AV, Wilbur R (1982) "Delirium and stereotypy from anticholinergic antiparkinson drugs." Prog Neuropsychopharmacol Biol Psychiatry, 6, p. 75-82
  15. (2001) "Product Information. Artane (trihexyphenidyl)." Lederle Laboratories

Food/lifestyle interactions

Moderate food/lifestyle interactions

Moderate:

haloperidol Food/Lifestyle

Applies to: haloperidol
Generally avoid

Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

Management

Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References (4)
  1. Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
  2. Gilman AG, eds., Nies AS, Rall TW, Taylor P (1990) "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: Pergamon Press Inc.
  3. (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
  4. (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka America Pharmaceutical, Inc.
Moderate:

brompheniramine Food/Lifestyle

Applies to: Unit-Hist Drops (brompheniramine / pseudoephedrine)
Generally avoid

Alcohol may potentiate some of the pharmacologic effects of CNS-active agents. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

Management

Patients receiving CNS-active agents should be warned of this interaction and advised to avoid or limit consumption of alcohol. Ambulatory patients should be counseled to avoid hazardous activities requiring complete mental alertness and motor coordination until they know how these agents affect them, and to notify their physician if they experience excessive or prolonged CNS effects that interfere with their normal activities.

References (4)
  1. Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
  2. Gilman AG, eds., Nies AS, Rall TW, Taylor P (1990) "Goodman and Gilman's the Pharmacological Basis of Therapeutics." New York, NY: Pergamon Press Inc.
  3. (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
  4. (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka America Pharmaceutical, Inc.
Moderate:

pseudoephedrine Caffeine

Applies to: Unit-Hist Drops (brompheniramine / pseudoephedrine)
Monitor

Coadministration of two or more sympathomimetic or noradrenergic agents may increase the risk of nervousness, irritability, tachycardia, and/or increased blood pressure. Central nervous system (CNS) stimulants, particularly amphetamines, can potentiate the adrenergic response to vasopressors and other sympathomimetic and/or noradrenergic agents, including norepinephrine transporter inhibitors. Additive increases in blood pressure and heart rate may occur due to enhanced peripheral sympathetic activity.

Management

Caution is advised if two or more sympathomimetic or noradrenergic agents are coadministered. Pulse and blood pressure should be closely monitored. Consultation with individual product labeling, as well as relevant institutional protocols, may be advisable for further guidance.

References (20)
  1. Rosenblatt JE, Lake CR, van Kammen DP, Ziegler MG, Bunney WE Jr (1979) "Interactions of amphetamine, pimozide, and lithium on plasma norepineophrine and dopamine-beta-hydroxylase in schizophrenic patients." Psychiatry Res, 1, p. 45-52
  2. Cavanaugh JH, Griffith JD, Oates JA (1970) "Effect of amphetamine on the pressor response to tyramine: formation of p-hydroxynorephedrine from amphetamine in man." Clin Pharmacol Ther, 11, p. 656
  3. (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
  4. (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
  5. (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
  6. (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
  7. (2024) "Product Information. Ephedrine (ephedrine)." Hameln Pharma Ltd
  8. (2023) "Product Information. Ephedrine Hydrochloride (ephedrine)." Wockhardt UK Ltd
  9. (2026) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
  10. (2025) "Product Information. Atomoxetine (atomoxetine)." Zentiva Pharma UK Ltd
  11. (2026) "Product Information. Atomoxetine (Apo) (atomoxetine)." Arrotex Pharmaceuticals Pty Ltd
  12. Angita Pharma, Inc (2026) AG-ATOMOXETINE Product Monograph (Health Canada) https://pdf.hres.ca/dpd_pm/00059014.PDF
  13. (2026) "Product Information. Boots Decongestant (Pseudoephedrine) (pseudoephedrine)." The Boots Company Plc
  14. (2023) "Product Information. Sinus and Nasal Decongestant (Trust) (pseudoephedrine)." Noumed Pharmaceuticals Pty Ltd
  15. (2019) "Product Information. Ephedrine (ephedrine)." Pfizer Australia Pty Ltd
  16. (2024) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Amneal Pharmaceuticals LLC
  17. (2024) "Product Information. Lemsip Cough Max for Mucus Cough and Cold (guaifenesin/paracetamol/phenylephrine)." Reckitt Benckiser Healthcare (UK) Ltd
  18. emc (2026) Product information: sudafed plus blocked nose 1mg/50mg/ml nasal spray. https://www.medicines.org.uk/emc/product/14256/smpc?utm_source=chatgpt.com
  19. (2023) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Baxter Corporation
  20. Neo Health (OTC) Pty Ltd (2026) Product information: pseudoephedrine hydrochloride-paracetamol capsules. https://www.ebs.tga.gov.au/ebs/picmi/picmirepository.nsf/pdf?OpenAgent&id=CP-2024-PI-02603-1&d=20260804172310101&d=20260827172310101
Moderate:

haloperidol Nicotine

Applies to: haloperidol
Monitor

Smoking cessation may lead to elevated plasma concentrations and enhanced pharmacologic effects of drugs that are substrates of CYP450 1A2 (and possibly CYP450 1A1) and/or certain drugs with a narrow therapeutic index (e.g., flecainide, pentazocine). One proposed mechanism is related to the loss of CYP450 1A2 and 1A1 induction by polycyclic aromatic hydrocarbons in tobacco smoke; when smoking cessation agents are initiated and smoking stops, the metabolism of certain drugs may decrease leading to increased plasma concentrations. The mechanism by which smoking cessation affects narrow therapeutic index drugs that are not known substrates of CYP450 1A2 or 1A1 is unknown. The clinical significance of this interaction is unknown as clinical data are lacking.

Management

Until more information is available, caution is advisable if smoking cessation agents are used concomitantly with drugs that are substrates of CYP450 1A2 or 1A1 and/or those with a narrow therapeutic range. Patients receiving smoking cessation agents may require periodic dose adjustments and closer clinical and laboratory monitoring of medications that are substrates of CYP450 1A2 or 1A1.

References (4)
  1. (2024) "Product Information. Cytisine (cytisinicline)." Consilient Health Ltd
  2. jeong sh, Newcombe D, sheridan j, Tingle M (2015) "Pharmacokinetics of cytisine, an a4 b2 nicotinic receptor partial agonist, in healthy smokers following a single dose." Drug Test Anal, 7, p. 475-82
  3. Vaughan DP, Beckett AH, Robbie DS (1976) "The influence of smoking on the intersubject variation in pentazocine elimination." Br J Clin Pharmacol, 3, p. 279-83
  4. Zevin S, Benowitz NL (1999) "Drug interactions with tobacco smoking: an update" Clin Pharmacokinet, 36, p. 425-38

Disease interactions

58 potential interactions Applies to: 40 conditions, including Underactive Thyroid, Asthma, Benign Prostatic Hyperplasia, COPD, and Angina.

Acute Alcohol Intoxication

Major:

haloperidol

Haloperidol has a major potential interaction with Acute Alcohol Intoxication.

The use of most miscellaneous antipsychotics is contraindicated in patients with severe central nervous system depression or comatose states from any cause (e.g., lesion, disease, drug or alcohol induced).

Alcoholism

Major:

haloperidol

Haloperidol has a major potential interaction with Alcoholism.

The use of neuroleptic agents is contraindicated in patients with acute alcohol intoxication exhibiting depressed vital signs. The central nervous system depressant effects of neuroleptic agents may be additive with those of alcohol. Severe respiratory depression and respiratory arrest may occur. Therapy with neuroleptic agents should be administered cautiously in patients who might be prone to acute alcohol intake.

Major:

haloperidol

Haloperidol has a major potential interaction with Alcoholism.

Antipsychotics can lower the seizure threshold and trigger seizures in a dose-dependent manner. Seizures have been reported in patients receiving antipsychotic therapy and may occur in epileptic patients even with maintenance of routine anticonvulsant treatment. Therapy with antipsychotics should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism. High dosages should be avoided if possible.

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Alcoholism.

Antipsychotic and neuroleptic drugs can lower the seizure threshold and trigger seizures in a dose-dependent manner. This risk is greatest in patients with a history of seizures or with conditions that lower the seizure threshold. Therapy with these drugs should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism.

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Alcoholism.

The use of alcohol with haloperidol should be avoided due to possible additive effects and hypotension.

Altered Consciousness

Major:

haloperidol

Haloperidol has a major potential interaction with Altered Consciousness.

The use of neuroleptic agents is contraindicated in comatose patients and patients with severe central nervous system depression. Neuroleptic agents may potentiate the CNS and respiratory depression in these patients.

Major:

haloperidol

Haloperidol has a major potential interaction with Altered Consciousness.

The use of most miscellaneous antipsychotics is contraindicated in patients with severe central nervous system depression or comatose states from any cause (e.g., lesion, disease, drug or alcohol induced).

Angina

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Angina.

Haloperidol should be administered cautiously to patients with severe cardiovascular disorders because of the possibility of transient hypotension and/or precipitation of anginal pain. In the presence of severe hypotension requiring vasopressor therapy, the preferred drugs may be norepinephrine, phenylephrine, or metaraminol, as usual doses of epinephrine may be ineffective since haloperidol inhibits its vasopressor effect.

Asthma

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Asthma.

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Benign Prostatic Hyperplasia

Moderate:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a moderate potential interaction with Benign Prostatic Hyperplasia.

Sympathomimetic agents may cause or worsen urinary difficulty in patients with prostate enlargement due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate.

Breast Cancer

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Breast Cancer.

The chronic use of neuroleptic agents can cause persistent elevations in prolactin levels due to antagonism of dopamine D2 receptors. Based on in vitro data, approximately one-third of human breast cancers are thought to be prolactin-dependent. The clinical significance of this observation with respect to long-term neuroleptic therapy is unknown. Chronic administration of neuroleptic drugs has been associated with mammary tumorigenesis in rodent studies but not in human clinical or epidemiologic studies. Until further data are available, therapy with neuroleptic agents should be administered cautiously in patients with a previously detected breast cancer. Caution is also advised in patients with preexisting hyperprolactinemia. Hyperprolactinemia may suppress hypothalamic gonadotrophin releasing hormone (GnRH), resulting in reduced pituitary gonadotropin secretion. This, in turn, may inhibit reproductive function by impairing gonadal steroidogenesis in both female and male patients. Galactorrhea, amenorrhea, gynecomastia, and impotence have been reported in patients receiving prolactin-elevating compounds; however, the clinical significance of elevated serum prolactin levels is unknown for most patients. Long-standing hyperprolactinemia when associated with hypogonadism may lead to decreased bone density in both female and male patients.

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Breast Cancer.

Antipsychotic drugs can elevate serum prolactin concentrations, and this elevation persists during chronic administration. This should be considered if therapy will be prescribed in patients with previously detected breast cancer as one-third of human breast cancers are prolactin-dependent in vitro. Associated disturbances such as galactorrhea, amenorrhea, gynecomastia, and impotence have been reported. Appropriate laboratory testing and follow-up is advised.

Cardiovascular Conditions and Disorders

Major:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a major potential interaction with Cardiovascular Conditions and Disorders.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Cardiovascular Conditions and Disorders.

Haloperidol should be administered cautiously to patients with severe cardiovascular disorders because of the possibility of transient hypotension and/or precipitation of anginal pain. In the presence of severe hypotension requiring vasopressor therapy, the preferred drugs may be norepinephrine, phenylephrine, or metaraminol, as usual doses of epinephrine may be ineffective since haloperidol inhibits its vasopressor effect.

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Cardiovascular Conditions and Disorders.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Central Nervous System Disorders

Major:

haloperidol

Haloperidol has a major potential interaction with Central Nervous System Disorders.

Antipsychotics can lower the seizure threshold and trigger seizures in a dose-dependent manner. Seizures have been reported in patients receiving antipsychotic therapy and may occur in epileptic patients even with maintenance of routine anticonvulsant treatment. Therapy with antipsychotics should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism. High dosages should be avoided if possible.

Cerebrovascular Insufficiency

Major:

haloperidol

Haloperidol has a major potential interaction with Cerebrovascular Insufficiency.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

Major:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a major potential interaction with Cerebrovascular Insufficiency.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

COPD

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with COPD.

It has been suggested that the anticholinergic effect of antihistamines may reduce the volume and cause thickening of bronchial secretions, resulting in obstruction of respiratory tract. Some manufacturers and clinicians recommend that therapy with antihistamines be administered cautiously in patients with asthma or chronic obstructive pulmonary disease.

Dehydration

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Dehydration.

Neuroleptic agents may cause hypotension (including orthostatic hypotension) and associated reflex tachycardia, syncope or dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few months. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Therapy with neuroleptic agents should be administered cautiously in patients with conditions that would predispose them to hypotension, such as hypovolemia or dehydration (e.g., due to severe diarrhea or vomiting). In addition, neuroleptic agents can interfere with the body's ability to regulate core body temperature, occasionally producing hyperthermia during strenuous exercise, exposure to hot weather, and concomitant treatment with anticholinergic medications. Patients who are dehydrated may be particularly susceptible.

Dementia

Major:

haloperidol

Haloperidol has a major potential interaction with Dementia.

Elderly patients with dementia- related psychosis treated with antipsychotic drugs are at increased risk of death. Most of these drugs are not approved for the treatment of patients with dementia- related psychosis.

Major:

haloperidol

Haloperidol has a major potential interaction with Dementia.

Antipsychotic drugs are not approved for the treatment of patients with dementia-related psychosis. Older patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death; although the causes were varied, most of the deaths appeared to be either cardiovascular (e.g., heart failure, sudden death) or infectious (e.g., pneumonia) in nature. A causal relationship with antipsychotic use has not been established. In controlled trials in older patients with dementia-related psychosis, patients randomized to risperidone, aripiprazole, and olanzapine had higher incidence of cerebrovascular adverse events (e.g., stroke, transient ischemic attack), including fatalities, compared to patients treated with placebo.

Diabetes Mellitus

Moderate:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a moderate potential interaction with Diabetes Mellitus.

Sympathomimetic agents may cause increases in blood glucose concentrations. These effects are usually transient and slight but may be significant with dosages higher than those normally recommended. Therapy with sympathomimetic agents should be administered cautiously in patients with diabetes mellitus. Closer monitoring of blood glucose concentrations may be appropriate.

Diarrhea

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Diarrhea.

Neuroleptic agents may cause hypotension (including orthostatic hypotension) and associated reflex tachycardia, syncope or dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few months. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Therapy with neuroleptic agents should be administered cautiously in patients with conditions that would predispose them to hypotension, such as hypovolemia or dehydration (e.g., due to severe diarrhea or vomiting). In addition, neuroleptic agents can interfere with the body's ability to regulate core body temperature, occasionally producing hyperthermia during strenuous exercise, exposure to hot weather, and concomitant treatment with anticholinergic medications. Patients who are dehydrated may be particularly susceptible.

Gastrointestinal Obstruction

Moderate:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a moderate potential interaction with Gastrointestinal Obstruction.

The extended-release formulation of pseudoephedrine (Sudafed 24 Hour) contains a non-deformable material. There have been rare reports of obstructive symptoms in patients with known strictures following the ingestion of similar sustained-release products. Therapy with the extended-release formulation of pseudoephedrine should be administered cautiously in patients with preexisting severe gastrointestinal narrowing or obstruction, whether pathologic or iatrogenic.

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Gastrointestinal Obstruction.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Glaucoma/Intraocular Hypertension

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Glaucoma/Intraocular Hypertension.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Moderate:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a moderate potential interaction with Glaucoma/Intraocular Hypertension.

Sympathomimetic agents can induce transient mydriasis via stimulation of alpha-1 adrenergic receptors. In patients with anatomically narrow angles or narrow-angle glaucoma, pupillary dilation can provoke an acute attack. In patients with other forms of glaucoma, mydriasis may occasionally increase intraocular pressure. Therapy with sympathomimetic agents should be administered cautiously in patients with or predisposed to glaucoma, particularly narrow-angle glaucoma.

Head Injury

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Head Injury.

Antipsychotic and neuroleptic drugs can lower the seizure threshold and trigger seizures in a dose-dependent manner. This risk is greatest in patients with a history of seizures or with conditions that lower the seizure threshold. Therapy with these drugs should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism.

Heart Disease

Major:

haloperidol

Haloperidol has a major potential interaction with Heart Disease.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

History - Cerebrovascular Disease

Major:

haloperidol

Haloperidol has a major potential interaction with History - Cerebrovascular Disease.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

History - Myocardial Infarction

Major:

haloperidol

Haloperidol has a major potential interaction with History - Myocardial Infarction.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

Hyperprolactinemia

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Hyperprolactinemia.

Antipsychotic drugs can elevate serum prolactin concentrations, and this elevation persists during chronic administration. This should be considered if therapy will be prescribed in patients with previously detected breast cancer as one-third of human breast cancers are prolactin-dependent in vitro. Associated disturbances such as galactorrhea, amenorrhea, gynecomastia, and impotence have been reported. Appropriate laboratory testing and follow-up is advised.

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Hyperprolactinemia.

The chronic use of neuroleptic agents can cause persistent elevations in prolactin levels due to antagonism of dopamine D2 receptors. Based on in vitro data, approximately one-third of human breast cancers are thought to be prolactin-dependent. The clinical significance of this observation with respect to long-term neuroleptic therapy is unknown. Chronic administration of neuroleptic drugs has been associated with mammary tumorigenesis in rodent studies but not in human clinical or epidemiologic studies. Until further data are available, therapy with neuroleptic agents should be administered cautiously in patients with a previously detected breast cancer. Caution is also advised in patients with preexisting hyperprolactinemia. Hyperprolactinemia may suppress hypothalamic gonadotrophin releasing hormone (GnRH), resulting in reduced pituitary gonadotropin secretion. This, in turn, may inhibit reproductive function by impairing gonadal steroidogenesis in both female and male patients. Galactorrhea, amenorrhea, gynecomastia, and impotence have been reported in patients receiving prolactin-elevating compounds; however, the clinical significance of elevated serum prolactin levels is unknown for most patients. Long-standing hyperprolactinemia when associated with hypogonadism may lead to decreased bone density in both female and male patients.

Hyperthyroidism

Major:

haloperidol

Haloperidol has a major potential interaction with Hyperthyroidism.

The use of neuroleptic agents in the presence of thyrotoxicosis has been associated with severe neurotoxicity that includes rigidity and inability to walk or talk. Therapy with haloperidol should be administered cautiously in patients with thyrotoxicosis or hyperthyroidism.

Major:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a major potential interaction with Hyperthyroidism.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Hyperthyroidism.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Hypokalemia

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Hypokalemia.

Cases of sudden death, QT interval prolongation and ventricular arrhythmias including Torsade de Pointes have been reported in patients using haloperidol. Although cases have been reported even in the absence of predisposing factors, special caution is advised in treating patients with other QT- prolonging conditions (including electrolyte imbalance such as hypokalemia and hypomagnesemia), using QT- prolonging drugs, with underlying cardiac abnormalities, hypothyroidism and familial long QT syndrome. Consider periodic EKG assessment on these patients. Treatment should be discontinued and a cardiac evaluation should be considered if a patient develops signs or symptoms of ventricular arrhythmia.

Hypotension

Major:

haloperidol

Haloperidol has a major potential interaction with Hypotension.

Neuroleptic agents may cause hypotension (including orthostatic hypotension), reflex tachycardia, increased pulse rate, syncope and dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few weeks. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Other reported adverse cardiovascular effects include hypertension, edema, arrhythmias, thrombophlebitis, myocarditis, angina, myocardial infarction, congestive heart failure, and ECG abnormalities such as PR and QT interval prolongation, diffuse T-wave flattening, and ST segment depression. Therapy with neuroleptic agents should be administered cautiously in patients with severe cardiovascular disease, pheochromocytoma, a predisposition to hypotension, or conditions that could be exacerbated by hypotension such as a history of myocardial infarction, angina, or ischemic stroke. Close monitoring of cardiovascular status, including ECG changes, is recommended at all dosages. If parenteral therapy is given, patients should be in a supine position during administration and for at least 30 to 60 minutes afterwards. Patients who experience orthostatic hypotension should be cautioned not to rise too abruptly. Occasionally, when severe, hypotension may require treatment with vasoconstrictive agents such as norepinephrine or phenylephrine. Epinephrine should not be used, however, since neuroleptic agents can reverse its vasopressor effects and cause a further lowering of blood pressure.

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Hypotension.

Antihistamines may infrequently cause cardiovascular adverse effects related to their anticholinergic and local anesthetic (quinidine-like) activities. Tachycardia, palpitation, ECG changes, arrhythmias, hypotension, and hypertension have been reported. Although these effects are uncommon and usually limited to overdosage situations, the manufacturers and some clinicians recommend that therapy with antihistamines be administered cautiously in patients with cardiovascular disease, hypertension, and/or hyperthyroidism.

Liver Disease

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Liver Disease.

Haloperidol appears to be primarily converted in the liver to several metabolites, one of which is believed to be pharmacologically active. The metabolites and approximately 1% of the parent drug are excreted in the urine. Patients with impaired renal and/or hepatic function may be at greater risk for adverse effects due to drug and metabolite accumulation. Therapy with haloperidol should be administered cautiously in such patients. Lower initial dosages and slower titration may be appropriate.

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Liver Disease.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Long QT Syndrome

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Long QT Syndrome.

Cases of sudden death, QT interval prolongation and ventricular arrhythmias including Torsade de Pointes have been reported in patients using haloperidol. Although cases have been reported even in the absence of predisposing factors, special caution is advised in treating patients with other QT- prolonging conditions (including electrolyte imbalance such as hypokalemia and hypomagnesemia), using QT- prolonging drugs, with underlying cardiac abnormalities, hypothyroidism and familial long QT syndrome. Consider periodic EKG assessment on these patients. Treatment should be discontinued and a cardiac evaluation should be considered if a patient develops signs or symptoms of ventricular arrhythmia.

Neuroleptic Malignant Syndrome

Major:

haloperidol

Haloperidol has a major potential interaction with Neuroleptic Malignant Syndrome.

The central dopaminergic blocking effects of neuroleptic agents may precipitate or aggravate a potentially fatal symptom complex known as neuroleptic malignant syndrome (NMS). NMS is observed most frequently when high-potency agents like haloperidol are administered intramuscularly, but may occur with any neuroleptic agent given for any length of time. Clinical manifestations of NMS include hyperpyrexia, muscle rigidity, altered mental status and autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis and cardiac arrhythmias). Additional signs may include elevated creatine phosphokinase, myoglobinuria, and acute renal failure. Neuroleptic agents should not be given to patients with active NMS and should be immediately discontinued if currently being administered in such patients. In patients with a history of NMS, introduction or reintroduction of neuroleptic agents should be carefully considered, since NMS may recur.

Major:

haloperidol

Haloperidol has a major potential interaction with Neuroleptic Malignant Syndrome.

Neuroleptic Malignant Syndrome (NMS), a potentially fatal symptom complex, has been reported in association with the use of antipsychotic drugs. The diagnostic evaluation is complicated and the management requires immediate discontinuation of the antipsychotic therapy and intensive symptomatic treatment and medical monitoring. If a patient that has recovered from NMS requires antipsychotic drug treatment again, the reintroduction of therapy should be carefully considered as NMS recurrences have been reported.

Neutropenia

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Neutropenia.

The use of antipsychotics has been associated with events of leukopenia, neutropenia and agranulocytosis. Possible risk factors include preexisting low white blood cell count, and history of drug induced leukopenia/neutropenia. Patients with these risk factors should have complete blood count monitored frequently during the first few months of therapy. Patients should also be monitored for any signs or symptoms of infection. Treatment should be discontinued in any patient who develops a sore throat, fever, stomatitis, or other signs of infection along with a low WBC count or severe neutropenia (ANC < 1000/mm3).

Parkinsonism

Major:

haloperidol

Haloperidol has a major potential interaction with Parkinsonism.

The use of neuroleptic agents is associated with pseudo- parkinsonian symptoms such as akinesia, bradykinesia, tremors, pill- rolling motion, cogwheel rigidity, and postural abnormalities including stooped posture and shuffling gait. The onset is usually 1 to 2 weeks following initiation of therapy or an increase in dosage. Older neuroleptic agents such as haloperidol are more likely to induce these effects. The manufacturers of haloperidol consider its use to be contraindicated in patients with Parkinson's disease.

Phenylketonuria

Moderate:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a moderate potential interaction with Phenylketonuria.

Chewable products frequently may contain aspartame, which is metabolized in the gastrointestinal tract to phenylalanine. Sudafed (brand of pseudoephedrine) chewable 15 mg tablets provide the equivalent of 0.78 mg of phenylalanine per each tablet. The aspartame/phenylalanine content should be considered when this and similar products are used in patients who must restrict their intake of phenylalanine (i.e. phenylketonurics).

Pheochromocytoma

Major:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a major potential interaction with Pheochromocytoma.

Sympathomimetic agents may cause adverse cardiovascular effects, particularly when used in high dosages and/or in susceptible patients. In cardiac tissues, these agents may produce positive chronotropic and inotropic effects via stimulation of beta- 1 adrenergic receptors. Cardiac output, oxygen consumption, and the work of the heart may be increased. In the peripheral vasculature, vasoconstriction may occur via stimulation of alpha-1 adrenergic receptors. Palpitations, tachycardia, arrhythmia, hypertension, reflex bradycardia, coronary occlusion, cerebral vasculitis, myocardial infarction, cardiac arrest, and death have been reported. Some of these agents, particularly ephedra alkaloids (ephedrine, ma huang, phenylpropanolamine), may also predispose patients to hemorrhagic and ischemic stroke. Therapy with sympathomimetic agents should generally be avoided or administered cautiously in patients with sensitivity to sympathomimetic amines, hyperthyroidism, or underlying cardiovascular or cerebrovascular disorders. These agents should not be used in patients with severe coronary artery disease or severe/uncontrolled hypertension.

Prostate Tumor, Benign

Moderate:

Unit-Hist Drops

The pseudoephedrine in Unit-Hist Drops has a moderate potential interaction with Prostate Tumor, Benign.

Sympathomimetic agents may cause or worsen urinary difficulty in patients with prostate enlargement due to smooth muscle contraction in the bladder neck via stimulation of alpha-1 adrenergic receptors. Therapy with sympathomimetic agents should be administered cautiously in patients with hypertrophy or neoplasm of the prostate.

Renal Dysfunction

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Renal Dysfunction.

Haloperidol appears to be primarily converted in the liver to several metabolites, one of which is believed to be pharmacologically active. The metabolites and approximately 1% of the parent drug are excreted in the urine. Patients with impaired renal and/or hepatic function may be at greater risk for adverse effects due to drug and metabolite accumulation. Therapy with haloperidol should be administered cautiously in such patients. Lower initial dosages and slower titration may be appropriate.

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Renal Dysfunction.

Limited pharmacokinetic data are available for the older, first-generation antihistamines. Many appear to be primarily metabolized by the liver, and both parent drugs and metabolites are excreted in the urine. Patients with renal and/or liver disease may be at greater risk for adverse effects from antihistamines due to drug and metabolite accumulation. Therapy with antihistamines should be administered cautiously in such patients. Lower initial dosages may be appropriate.

Respiratory Arrest

Major:

haloperidol

Haloperidol has a major potential interaction with Respiratory Arrest.

The use of neuroleptic agents is contraindicated in comatose patients and patients with severe central nervous system depression. Neuroleptic agents may potentiate the CNS and respiratory depression in these patients.

Seizures

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Seizures.

Antipsychotic and neuroleptic drugs can lower the seizure threshold and trigger seizures in a dose-dependent manner. This risk is greatest in patients with a history of seizures or with conditions that lower the seizure threshold. Therapy with these drugs should be administered cautiously in patients with a history of seizures or other predisposing factors, such as head trauma, CNS abnormalities, and alcoholism.

Tardive Dyskinesia

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Tardive Dyskinesia.

Tardive dyskinesia (TD) has occurred in patients treated with antipsychotic drugs; the syndrome consists of potentially irreversible, involuntary, dyskinetic movements. The risk appears highest in older patients (particularly older women) but it is not possible to predict which patients are likely to develop TD; whether antipsychotic drugs differ in their potential to cause TD is unknown. The risk of TD and the likelihood that it will become irreversible increase with the duration of therapy and the total cumulative dose. The syndrome can develop after relatively brief treatment periods, even at low dosages; it may also occur after discontinuation of therapy. TD may remit (partially or completely) upon discontinuation of antipsychotic therapy, although antipsychotic therapy itself may suppress (or partially suppress) signs/symptoms of TD, possibly masking the underlying process; the effect of symptomatic suppression on the long-term course of TD is unknown. In patients with preexisting drug-induced TD, initiating or increasing the dosage of antipsychotic therapy may temporarily mask the symptoms of TD but could eventually worsen the condition. In patients requiring chronic therapy, the lowest dose and shortest duration of therapy producing a satisfactory clinical response are recommended; the need for continued therapy should be reassessed periodically. If signs/symptoms of TD occur during antipsychotic therapy, discontinuation of the offending agent should be considered; however, some patients may require treatment despite the presence of TD.

Underactive Thyroid

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Underactive Thyroid.

Cases of sudden death, QT interval prolongation and ventricular arrhythmias including Torsade de Pointes have been reported in patients using haloperidol. Although cases have been reported even in the absence of predisposing factors, special caution is advised in treating patients with other QT- prolonging conditions (including electrolyte imbalance such as hypokalemia and hypomagnesemia), using QT- prolonging drugs, with underlying cardiac abnormalities, hypothyroidism and familial long QT syndrome. Consider periodic EKG assessment on these patients. Treatment should be discontinued and a cardiac evaluation should be considered if a patient develops signs or symptoms of ventricular arrhythmia.

Urinary Retention

Moderate:

Unit-Hist Drops

The brompheniramine in Unit-Hist Drops has a moderate potential interaction with Urinary Retention.

Antihistamines often have anticholinergic activity, to which elderly patients are particularly sensitive. Therapy with antihistamines should be administered cautiously, if at all, in patients with preexisting conditions that are likely to be exacerbated by anticholinergic activity, such as urinary retention or obstruction; angle-closure glaucoma, untreated intraocular hypertension, or uncontrolled primary open-angle glaucoma; and gastrointestinal obstructive disorders. Conventional, first-generation antihistamines such as the ethanolamines (bromodiphenhydramine, carbinoxamine, clemastine, dimenhydrinate, diphenhydramine, doxylamine, phenyltoloxamine) tend to exhibit substantial anticholinergic effects. In contrast, the newer, relatively nonsedating antihistamines (e.g., cetirizine, fexofenadine, loratadine) reportedly have low to minimal anticholinergic activity at normally recommended dosages and may be appropriate alternatives.

Vomiting

Moderate:

haloperidol

Haloperidol has a moderate potential interaction with Vomiting.

Neuroleptic agents may cause hypotension (including orthostatic hypotension) and associated reflex tachycardia, syncope or dizziness, particularly during initiation of therapy or rapid escalation of dosage. Tolerance to the hypotensive effects often develops after a few doses to a few months. Rarely, fatal cardiac arrest has occurred secondary to severe hypotension. Therapy with neuroleptic agents should be administered cautiously in patients with conditions that would predispose them to hypotension, such as hypovolemia or dehydration (e.g., due to severe diarrhea or vomiting). In addition, neuroleptic agents can interfere with the body's ability to regulate core body temperature, occasionally producing hyperthermia during strenuous exercise, exposure to hot weather, and concomitant treatment with anticholinergic medications. Patients who are dehydrated may be particularly susceptible.

More resources

haloperidol

A total of 784 drugs are known to interact with haloperidol.

Unit-Hist Drops

A total of 517 drugs are known to interact with Unit-Hist Drops.

Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.