Interactions between Flibanserin and Phenylephrine / pyrilamine
1 drug interaction and 29 additional warnings found for the following 2 drugs:
- flibanserin
- phenylephrine/pyrilamine
Drug interactions
Moderate drug interactions
Moderate:
pyrilamine flibanserin
Applies to: phenylephrine / pyrilamine and flibanserin
Monitor
The central nervous system (CNS) effects of flibanserin such as somnolence and fatigue may be potentiated by concomitant use of other agents with CNS depressant effects. In five 24-week clinical trials, the incidence of somnolence, sedation, or fatigue was 21% and 8% in patients treated with flibanserin 100 mg once daily at bedtime and placebo, respectively. The risk of CNS depression is increased if flibanserin is taken during waking hours or with alcohol or other CNS depressants.
Management
Patients receiving flibanserin with other agents that can cause CNS depression should be apprised of the potential for increased adverse effects such as drowsiness, dizziness, lightheadedness, and fatigue. Patients should not drive, operate machinery, or engage in hazardous activities requiring mental alertness and motor coordination for at least 6 hours after taking flibanserin and until they know how the medication affects them.
References (1)
- (2015) "Product Information. Addyi (flibanserin)." Sprout Pharmaceuticals
Food/lifestyle interactions
Major food/lifestyle interactions
Major:
flibanserin Food/Lifestyle
Applies to: flibanserin
Contraindicated
Grapefruit juice may increase the plasma concentrations of flibanserin. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruit. In 26 healthy female subjects, administration of a single 100 mg dose of flibanserin with 240 mL grapefruit juice increased flibanserin peak plasma concentration (Cmax) and systemic exposure (AUC) by 1.1- and 1.4-fold, respectively, compared to administration of flibanserin alone. In general, the effect of grapefruit juice is concentration-, dose- and preparation-dependent, and can vary widely among brands. Certain preparations of grapefruit juice (e.g., high dose, double strength) have sometimes demonstrated potent inhibition of CYP450 3A4, while other preparations (e.g., low dose, single strength) have typically demonstrated moderate inhibition.
Adjust dosing interval
Coadministration of flibanserin with alcohol may potentiate the risk of severe hypotension, syncope, and central nervous system depression. In a dedicated alcohol interaction study, hypotension or syncope requiring therapeutic intervention (ammonia salts and/or placement in supine or Trendelenberg position) occurred in 4 (17%) of 23 subjects given flibanserin 100 mg with 0.4 g/kg alcohol (equivalent to two 12 ounce cans of beer containing 5% alcohol content, two 5 ounce glasses of wine containing 12% alcohol content, or two 1.5 ounce shots of 80-proof spirit in a 70 kg person) consumed over 10 minutes in the morning. In these four subjects, systolic blood pressure reductions ranged from 28 to 54 mmHg and diastolic blood pressure reductions ranged from 24 to 46 mmHg. In addition, 6 (25%) of 24 subjects coadministered flibanserin with 0.8 g/kg alcohol experienced orthostatic hypotension when standing from a sitting position. Systolic and diastolic blood pressure reductions in these 6 subjects ranged from 22 to 48 mmHg and 0 to 27 mmHg, respectively, with one requiring therapeutic intervention. No adverse events requiring therapeutic intervention were observed when flibanserin or alcohol was administered alone. Somnolence was reported in 67%, 74%, and 92% of subjects who received flibanserin alone, flibanserin with 0.4 g/kg ethanol, and flibanserin with 0.8 g/kg ethanol, respectively. Subsequent data from postmarketing trials showed that the risk of severe hypotension and syncope was reduced when women who consumed up to two alcoholic drinks waited at least two hours before taking flibanserin.
Management
Concomitant use of flibanserin with moderate or potent CYP450 3A4 inhibitors such as grapefruit juice is considered contraindicated. The patient should be advised to avoid the consumption of grapefruit and grapefruit juice during treatment, and to take flibanserin at bedtime to minimize the risk of hypotension, syncope, accidental injury, and central nervous system depression. In addition, patients should consume no more than 1 to 2 alcoholic drinks and discontinue drinking alcohol at least two hours before taking flibanserin at bedtime; otherwise, they should skip the flibanserin dose that evening. Alcohol should not be consumed until at least the morning after taking flibanserin at bedtime. A standard alcoholic drink contains 14 g of pure alcohol and is equivalent to one 12-ounce regular beer (5% alcohol), 5-ounces wine (12% alcohol), or 1.5 ounces of distilled spirits/shot (40% alcohol).
References (1)
- (2015) "Product Information. Addyi (flibanserin)." Sprout Pharmaceuticals
Moderate food/lifestyle interactions
Moderate:
pyrilamine Food/Lifestyle
Applies to: phenylephrine / pyrilamine
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)
- Warrington SJ, Ankier SI, Turner P (1986) "Evaluation of possible interactions between ethanol and trazodone or amitriptyline." Neuropsychobiology, 15, p. 31-7
- 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.
- (2012) "Product Information. Fycompa (perampanel)." Eisai Inc
- (2015) "Product Information. Rexulti (brexpiprazole)." Otsuka America Pharmaceutical, Inc.
Moderate:
phenylephrine Caffeine
Applies to: phenylephrine / pyrilamine
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)
- 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
- 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
- (2001) "Product Information. Adderall (amphetamine-dextroamphetamine)." Shire Richwood Pharmaceutical Company Inc
- (2001) "Product Information. Tenuate (diethylpropion)." Aventis Pharmaceuticals
- (2001) "Product Information. Sanorex (mazindol)." Novartis Pharmaceuticals
- (2001) "Product Information. Focalin (dexmethylphenidate)." Mikart Inc
- (2024) "Product Information. Ephedrine (ephedrine)." Hameln Pharma Ltd
- (2023) "Product Information. Ephedrine Hydrochloride (ephedrine)." Wockhardt UK Ltd
- (2026) "Product Information. Strattera (atomoxetine)." Lilly, Eli and Company
- (2025) "Product Information. Atomoxetine (atomoxetine)." Zentiva Pharma UK Ltd
- (2026) "Product Information. Atomoxetine (Apo) (atomoxetine)." Arrotex Pharmaceuticals Pty Ltd
- Angita Pharma, Inc (2026) AG-ATOMOXETINE Product Monograph (Health Canada) https://pdf.hres.ca/dpd_pm/00059014.PDF
- (2026) "Product Information. Boots Decongestant (Pseudoephedrine) (pseudoephedrine)." The Boots Company Plc
- (2023) "Product Information. Sinus and Nasal Decongestant (Trust) (pseudoephedrine)." Noumed Pharmaceuticals Pty Ltd
- (2019) "Product Information. Ephedrine (ephedrine)." Pfizer Australia Pty Ltd
- (2024) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Amneal Pharmaceuticals LLC
- (2024) "Product Information. Lemsip Cough Max for Mucus Cough and Cold (guaifenesin/paracetamol/phenylephrine)." Reckitt Benckiser Healthcare (UK) Ltd
- 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
- (2023) "Product Information. EPHEDrine Sulfate (ePHEDrine)." Baxter Corporation
- 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
Disease interactions
26 potential interactions Applies to: 18 conditions, including Depression, Asthma, Benign Prostatic Hyperplasia, COPD, and Hypotension.
Alcoholism
Major:
flibanserin
Flibanserin has a major potential interaction with Alcoholism.
The use of flibanserin is contraindicated along with the ingestion of alcohol, as it increases the risk of hypotension and syncope. It is important to assess the likelihood of the patient abstaining from alcohol, taking into account the current and past drinking behavior.
Asthma
Moderate:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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.
Cardiovascular Conditions and Disorders
Major:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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.
Cerebrovascular Insufficiency
Major:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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.
Depression
Major:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine has a major potential interaction with Depression.
A variety of abnormal thinking and behavior changes have been reported to occur in association with the use of most anxiolytics, sedatives and hypnotics. Some of these changes include decreased inhibition, aggressiveness, agitation, and hallucinations. These drugs can cause or exacerbate mental depression and cause suicidal behavior and ideation. Therapy with these drugs should be administered cautiously in patients with a history of depression or other psychiatric disorders. Patients should be monitored for any changes in mood or behavior. It may be prudent to refrain from dispensing large quantities of medication to these patients.
Diabetes Mellitus
Moderate:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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.
Gastrointestinal Obstruction
Moderate:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine has a moderate potential interaction with Glaucoma/Intraocular Hypertension.
Some hypnotic drugs can have an anticholinergic effect and should be used with caution in patients with glaucoma, and trouble urinating due to retention or enlarged prostate.
Moderate:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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.
Hyperthyroidism
Major:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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.
Hypotension
Major:
flibanserin
Flibanserin has a major potential interaction with Hypotension.
The use of flibanserin can cause hypotension and syncope. The benefits and risks of therapy should be considered in patients with preexisting conditions that predispose to hypotension. Flibanserin should be used with caution in these patients.
Moderate:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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
Major:
flibanserin
Flibanserin has a major potential interaction with Liver Disease.
Flibanserin may accumulate in patients with hepatic impairment. Therapy with flibanserin is contraindicated in patients with compromised hepatic function.
Moderate:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine has a moderate potential interaction with Liver Disease.
In general, anxiolytics, sedatives and hypnotics are extensively metabolized by the liver. Their plasma clearance may be decreased and their half-life prolonged in patients with impaired hepatic function. Therapy with these drugs should be administered cautiously in patients with liver disease (some are not recommended in severe liver impairment), and the dosage should be adjusted accordingly. Laboratory testing is recommended prior and during treatment.
Moderate:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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.
Pheochromocytoma
Major:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The phenylephrine in phenylephrine / pyrilamine 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:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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.
Syncope
Major:
flibanserin
Flibanserin has a major potential interaction with Syncope.
The use of flibanserin can cause hypotension and syncope. The benefits and risks of therapy should be considered in patients with preexisting conditions that predispose to hypotension. Flibanserin should be used with caution in these patients.
Urinary Retention
Moderate:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine 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.
Moderate:
phenylephrine / pyrilamine
The pyrilamine in phenylephrine / pyrilamine has a moderate potential interaction with Urinary Retention.
Some hypnotic drugs can have an anticholinergic effect and should be used with caution in patients with glaucoma, and trouble urinating due to retention or enlarged prostate.
More resources
flibanserin
A total of 517 drugs are known to interact with flibanserin.
- Flibanserin is in the drug class miscellaneous central nervous system agents.
- Flibanserin is used to treat Hypoactive Sexual Desire Disorder.
phenylephrine / pyrilamine
A total of 570 drugs are known to interact with phenylephrine / pyrilamine.
- Phenylephrine / pyrilamine is in the drug class upper respiratory combinations.
- Phenylephrine / pyrilamine is used to treat the following conditions:
Drug Interaction Classification
| Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. | |
| Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. | |
| 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. | |
| No interaction information available. |
Further information
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.