Skip to Content

Duohist DH

Generic name: dihydrocodeine bitartrate, chlorpheniramine maleate and phenylephrine hydrochloride
Dosage form: liquid

Medically reviewed by Last updated on Sep 21, 2020.

Disclaimer: This drug has not been found by FDA to be safe and effective, and this labeling has not been approved by FDA. For further information about unapproved drugs, click here.

Antitussive • Antihistamine • Decongestant

Rx Only


Duohist™ DH is a sugar free, alcohol free, dye free, clear, strawberry flavored liquid.

Each 5 mL (one teaspoonful) for oral administration contains:

(WARNING - May be habit forming)
Dihydrocodeine Bitartrate* 7.25 mg
Chlorpheniramine Maleate 2 mg
Phenylephrine Hydrochloride 5 mg

Inactive Ingredients: Citric acid, Sodium benzoate, Saccharin sodium, Sorbitol, Propylene glycol, Strawberry flavor and Purified water.

Dihydrocodeine Bitartrate is an opioid analgesic and antitussive that occurs as an odorless, fine white powder. Its chemical name is: Morphinan-6-ol, 4,5-epoxy-3-methoxy-17 -methyl-,(5α,6α)-2,3-dihydroxybutanedioate (1:1) (salt). Its structure is as follows:

C18H23NO3 • C4H6O6 M.W. 451.47

Phenylephrine Hydrochloride is an orally effective nasal decongestant having the chemical name, Benzenemethanol, 3-hydroxy-α-[(methylamino)methyl]-, hydrochloride (R)-, with the following structure:

C9H13NO2 • HCl M.W. 203.67

Chlorpheniramine Maleate is an antihistamine having the chemical name: 2-Pyridinepropanamine, γ-(4-chlorophenyl)-N,N-dimethyl-, (Z)-2-butenedioate (1:1). and has the following chemical formula:

C16H19ClN2 • C4H4O4 M.W. 390.86

Duohist DH - Clinical Pharmacology

Dihydrocodeine bitartrate is a semi-synthetic narcotic analgesic related to codeine, with multiple actions qualitatively similar to those of codeine; the most prominent of these involve the central nervous system and organs with smooth muscle components.

Chlorpheniramine maleate is an alkylamine type antihistamine. This group of antihistamines is among the most active histamine antagonists and is generally effective in relatively low doses. These drugs are not so prone to produce drowsiness and are among the most suitable agents for daytime use, but a significant proportion of patients do experience this effect.

Phenylephrine hydrochloride is a sympathomimetic, which acts predominately on alpha-receptors and has little action on beta-receptors. It therefore functions as an oral nasal decongestant with minimal CNS stimulation.

Indications and Usage for Duohist DH

Duohist™ DH Liquid is indicated to control cough and provide for temporary relief from congestion associated with the upper respiratory tract.


Duohist™ DH is contraindicated in patients with hypersensitivity to dihydrocodeine, chlorpheniramine maleate, phenylephrine hydrochloride or any of the inactive components listed above, or in any situation where opioids are contraindicated including significant respiratory depression (in unmonitored settings or in the absence of resuscitation equipment), acute or severe bronchial asthma or hypercapnia, and paralytic ileus.

Antihistamines and sympathomimetics are contraindicated in patients receiving antihypertensive or antidepressant drugs containing monoamine oxidase inhibitors (MAOI)s (or for 14 days after stopping MAOI therapy). Antihistamines should not be used to treat lower respiratory tract symptoms or be given to premature or newborn infants. Sympathomimetic agents are contraindicated in patients with severe hypertension, severe coronary artery disease, patients with narrow angle glaucoma, bronchial asthma, urinary retention, peptic ulcer, and during an asthma attack. This product is contraindicated in women who are pregnant.



Do not exceed recommended dosage. If nervousness, dizziness, or sleeplessness occurs, discontinue use and consult a doctor. If symptoms do not improve within 7 days or are accompanied by a fever, consult a doctor.

Considerable caution should be exercised in patients with hypertension, diabetes mellitus, ischemic heart disease, hyperthyroidism, increased intraocular pressure and prostatic hypertrophy. The elderly (60 years and older) are more likely to exhibit adverse reactions. Antihistamines may cause excitability, especially in children. At dosages higher than the recommended dose, nervousness, dizziness, or sleeplessness may occur.

Stimulants, such as phenylephrine, are banned and tested for by the U.S. Olympic Committee (USOC) and the National Collegiate Athletic Association (NCAA).

Usage in Ambulatory Patients

Dihydrocodeine may impair the mental and/or physical abilities required for the performance of potentially hazardous tasks such as driving a car or operating machinery.

Respiratory Depression

Respiratory depression is the most dangerous acute reaction produced by opioid agonist preparations, although it is rarely severe with usual doses. Opioids decrease the respiratory rate, tidal volume, minute ventilation, and sensitivity to carbon dioxide. Respiratory depression occurs most frequently in elderly more debilitated patients, usually after large initial doses in non-tolerant patients, or when opioids are given in conjunction with other agents that depress respiration. This combination product should be used with caution in patients with significant chronic obstructive pulmonary disease or cor pulmonale and in patients with a substantially decreased respiratory reserve, hypoxia hypercapnia, or respiratory depression.

Hypotensive Effect

Dihydrocodeine, like all opioid analgesics, may cause hypotension in patients whose ability to maintain blood pressure has been compromised by a depleted blood volume or who receive concurrent therapy with drugs such as phenothiazines or other agents which compromise vasomotor tone. Duohist™ DH may produce orthostatic hypotension in ambulatory patients. This combination product should be administered with caution to patients in circulatory shock, since vasodilation produced by the drug may further reduce cardiac output and blood pressure.


Dihydrocodeine can produce drug dependence of the codeine type and has the potential of being abused. This product should be prescribed and administered with the appropriate degree of caution. (See DRUG ABUSE AND DEPENDENCE section).



This combination product should be used with caution in elderly or debilitated patients or those with any of the following conditions: adrenocortical insufficiency (e.g., Addison's disease); asthma; central nervous system depression or coma; chronic obstructive pulmonary disease; decreased respiratory reserve (including emphysema, severe obesity, cor pulmonale, or kyphoscoliosis); delirium tremens; diabetes; head injury; hypotension; hypertension; increased intracranial pressure; myxedema or hypothyroidism; prostatic hypertrophy or urethral, stricture; and toxic psychosis. The benefits and risks of opioids in patients taking monoamine oxidase inhibitors (or for 14 days after stopping MAOI therapy) and in those with a history of drug abuse should be carefully considered. This combination product may aggravate convulsions in patients with convulsive disorders, and, like all opioids, may induce or aggravate seizures in some clinical settings.

Drug Interactions

Sympathomimetics may reduce the antihypertensive effects of methyldopa, mecamylamine, reserpine and veratrum alkaloids.

Other Central Nervous System Depressants

Patients receiving other opioid analgesics, sedatives or hypnotics, muscle relaxants, general anesthetics, centrally acting antiemetics, phenothiazines or other tranquilizers, or alcohol concomitantly with this combination product may exhibit additive depressant effects on the central nervous system. When such combined therapy is contemplated, the dose of one or both agents should be reduced. Concomitant use of hydrocodeine and antihistamines with alcohol and other CNS depressants may have an additive effect.

Monoamine Oxidase inhibitors (or for 14 days after stopping MAOI therapy)

Dihydrocodeine, like all opioids, interact with monoamine oxidase inhibitors causing central nervous system excitation and hypertension. MAOIs and beta-adrenergic blockers increase the effects of sympathomimetics. They may also prolong and intensify the anticholinergic effects of antihistamines.

Information for Patients/Caregivers

Patients receiving Duohist™ DH should be given the following information:

  • Patients should be advised that Duohist™ DH may impair the mental or physical abilities required for the performance of potentially hazardous tasks such as driving a car or operating machinery.
  • Patients should be advised to report adverse experiences occurring during therapy.
  • Patients should be advised not to adjust the dose of Duohist™ DH without consulting the prescribing professional.
  • Patients should not combine Duohist™ DH with alcohol or other central nervous system depressants.
  • Women of childbearing potential who become, or are planning to become pregnant should be advised to consult their physician regarding the effects of opioids and other drug use during pregnancy on themselves and their unborn child.

Patients should be advised that Duohist™ DH is a potential drug of abuse. They should protect it from theft, and it should never be given to anyone other than the individual for whom it was prescribed.


Codeine Warning

When physicians prescribe codeine-containing drugs to nursing women, they should inform their patients about the potential risks and the signs of morphine overdose. Nursing women taking codeine need to carefully watch their infants for signs of morphine overdose and seek medical attention immediately if the infant develops increased sleepiness (more than usual), difficulty breast feeding or breathing, or decreased tone (limpness). Nursing mothers may also experience overdose symptoms such as extreme sleepiness, confusion, shallow breathing or severe constipation. When prescribing codeine to nursing mothers, physicians should choose the lowest effective dose for the shortest period of time and should closely monitor mother-infant pairs.

Drug metabolism is a complex process involving multiple genetic, environmental and physiologic factors.

Limited evidence suggests that individuals who are ultra-rapid metabolizers (those with a specific CYP2D6 genotype) may convert codeine to its active metabolite, morphine, more rapidly and completely than other people. In nursing mothers, this metabolism can result in higher than expected serum and breast milk morphine levels. One published case report of an infant death raises concern that nursing babies may be at increased risk of morphine overdose if their mothers are taking codeine and are ultra-rapid metabolizers of the drug.


Teratogenic Effects

Category C

Animal reproduction studies have not been conducted with Duohist™ DH. It is also not known whether this combination product can cause fetal harm when administered to pregnant women or can affect reproduction capacity in males and females. This combination product should be given to pregnant women only if clearly needed, especially during the first trimester.

Nonteratogenic Effects

Babies born to mothers who have been taking opioids regularly prior to delivery will be physically dependent. The withdrawal signs include irritability and excessive crying, tremors, hyperactive reflexes, increased respiratory rate, increased stools, sneezing, yawning, vomiting and fever. The intensity of the syndrome does not always correlate with the duration of maternal opioid use or dose. There is no consensus on the best method of managing withdrawal. Chlorpromazine 0.7-1.0 mg/kg q6h, phenobarbital 2 mg/kg q6h, and paregoric 2-4 drops/kg q4h, have been used to treat withdrawal symptoms in infants. The duration of therapy is 4 to 28 days, with the dosages decreased as tolerated.

Labor and Delivery

Duohist™ DH is not recommended for use by women during and immediately before labor and delivery because oral opioids may cause respiratory depression in the newborn.

Pediatric Use

Safety and effectiveness in the pediatric population, under 6, have not been established. Children under 2 years may be more susceptible to respiratory arrest, coma and death. Use of antihistamines is not recommended in infants. This age group may be at a higher risk than other age groups because of an increased susceptibility to anticholinergic effects, such as CNS excitation, and an increased tendency toward convulsions. In older children taking antihistamines, a paradoxical reaction characterized by hyperexcitability may occur. Very young children may be more sensitive to the effects, especially the vasopressor effects of sympathomimetic amines.

Geriatric Use

Duohist™ DH should be given with caution to the elderly.

Hepatic Impairment

Duohist™ DH should be given with caution to patients with hepatic insufficiency. Since, dihydrocodeine is metabolized by the liver, the effects of this combination product should be monitored closely in such patients.

Renal Impairment

Duohist™ DH should be used with caution and at reduced dosage in the presence of impaired renal function.

Pancreatic/Biliary Tract Disease

Opioids may cause spasms of the sphincter of Oddi and should be used with caution in patients with biliary tract disease including pancreatitis.

Adverse Reactions

The most frequently observed adverse reactions with hydrocodeine include lightheadedness, dizziness, drowsiness, headache, fatigue, sedation, sweating, nausea, vomiting, constipation, pruritus, and skin reactions. With the exception of constipation, tolerance develops to most of these effects. Other reactions that have been observed with dihydrocodeine or other opioids include respiratory depression, orthostatic hypotension, cough suppression, confusion, diarrhea, miosis, abdominal pain, dry mouth, indigestion, anorexia, spasm of biliary tract, and urinary retention. Physical and psychological dependence are possibilities. Hypersensitivity reactions (including anaphylactoid reactions), hallucinations, vivid dreams, granulomatous interstitial nephritis, severe narcosis and acute renal failure have been reported rarely during dihydrocodeine administration.

Other adverse reactions observed with the ingredients in Duohist™ DH include, lassitude, nausea, giddiness, dryness of mouth, blurred vision, cardiac palpitations, flushing, increased irritability or excitement (especially in children).

Drug Abuse and Dependence

This combination product is subject to the provisions of the Controlled Substance Act and has been placed in Schedule III. Dihydrocodeine can produce drug dependence of the codeine type and therefore has the potential of being abused. Psychological dependence, physical dependence, and tolerance may develop upon repeated administration of dihydrocodeine, and it should be prescribed and administered with the same degree of caution appropriate to the use of other oral opioid medications. Symptoms of dihydrocodeine withdrawal consist of irritability, restlessness, insomnia, diaphoresis, anxiety and palpitations.


An overdose of Duohist™ DH is a potentially lethal polydrug overdose situation, and consultation with a regional Poison Control Center is recommended. A listing of the poison control centers can be found in standard references such as the "Physician's Desk Reference®".

Signs and Symptoms

Symptoms of overdosage include pinpoint pupils, respiratory depression, extreme somnolence progressing to stupor, loss of consciousness, or coma, skeletal muscle flaccidity, cold and clammy skin and other symptoms common with narcotic overdosage. Convulsions, cardiovascular collapse, and death may occur. A single case of acute rhabdomyolysis associated with an overdose of dihydrocodeine has been reported.

Recommended Treatment

Immediate treatment of an overdosage of Duohist™ DH includes support of cardiorespiratory function and measures to reduce drug absorption. Vomiting should be induced with syrup of ipecac, if the patient is alert and has adequate laryngeal reflexes. Oral activated charcoal should follow. The first dose should be accompanied by an appropriate cathartic. Gastric lavage may be necessary. Hypotension is usually hypovolemic and should be treated with fluids. Endotracheal intubation and artificial respiration may be necessary. The pure opioid antagonist naloxone or nalmefene is a specific antidote against respiratory depression that results from opioid overdose. Opioid antagonists should not be given in the absence of clinically significant respiratory or circulatory depression secondary to opioid overdose. They should be administered cautiously to persons who are known, or suspected to be, physically dependent on any opioid agonist including dihydrocodeine. In such cases, an abrupt or complete reversal of opioid effects may precipitate an acute abstinence syndrome. The prescribing information for the specific opioid antagonist should be consulted for details of their proper use.

Duohist DH Dosage and Administration

Adults and adolescents over 12 years of age

1 to 2 teaspoonsful (5 mL to 10 mL) every 4-6 hours. Not to exceed 8 teaspoonsful (40 mL) in 24 hours.

Children 6 to 12 years of age

1/2 to 1 teaspoonful (2.5 mL to 5 mL) every 4-6 hours. Not to exceed 4 teaspoonsful (20 mL) in 24 hours.

This product is not indicated for use in children under 6 years of age. (See Precautions, Pediatric Use.)

How is Duohist DH Supplied

Duohist™ DH is a sugar free, alcohol free, dye free, clear, strawberry flavored liquid. Available in bottles of 16 fl. oz.(473 mL), NDC 51991-598-16.



Store at 25° C (77° F ); excursions permitted to 15° - 30°C (59° - 86° F). See USP Controlled Room Temperature. Protect from freezing.


Dispense in a tight, light-resistant container with a child-resistant closure as defined in the USP/NF.

Rx Only

All prescription substitutions using this product shall be pursuant to state statutes as applicable. This is not an Orange Book product.

Distributed by:
Breckenridge Pharmaceutical, Inc.
Boca Raton, FL 33487

Manufactured by:
Deltex Pharmaceuticals, Inc.
Rosenberg, TX 77471

ISS. 04/08


Pharmaceutical, Inc.

NDC 51991-598-16


Duohist™ DH

Antitussive • Antihistamine

Each 5 mL (1 teaspoonful) for
oral administration contains:
Dihydrocodeine Bitartrate* ..... 7.25 mg
*(Warning: May be habit-forming)
Chlorpheniramine Maleate ..... 2 mg
Phenylephrine Hydrochloride ..... 5 mg


Rx Only

Net Contents

16 fl. oz. (One Pint) 473 mL

dihydrocodeine bitartrate, chlorpheniramine maleate and phenylephrine hydrochloride liquid
Product Information
Product Type HUMAN PRESCRIPTION DRUG LABEL Item Code (Source) NDC:51991-598
Route of Administration ORAL DEA Schedule CIII
Active Ingredient/Active Moiety
Ingredient Name Basis of Strength Strength
Dihydrocodeine Bitartrate (Dihydrocodeine) Dihydrocodeine Bitartrate 7.5 mg in 5 mL
Chlorpheniramine Maleate (Chlorpheniramine) Chlorpheniramine Maleate 2 mg in 5 mL
Phenylephrine Hydrochloride (Phenylephrine) Phenylephrine Hydrochloride 5 mg in 5 mL
Inactive Ingredients
Ingredient Name Strength
Citric Acid Monohydrate
Sodium Benzoate
Saccharin Sodium
Propylene Glycol
Product Characteristics
Color Score
Shape Size
Flavor STRAWBERRY Imprint Code
# Item Code Package Description
1 NDC:51991-598-16 473 mL in 1 BOTTLE, PLASTIC
Marketing Information
Marketing Category Application Number or Monograph Citation Marketing Start Date Marketing End Date
Unapproved other 04/01/2008
Labeler - Breckenridge Pharmaceutical, Inc. (150554335)
Name Address ID/FEI Operations
Deltex Pharmaceuticals 019851778 MANUFACTURE
Breckenridge Pharmaceutical, Inc.

More about Duohist DH (chlorpheniramine / dihydrocodeine / phenylephrine)

Professional resources

Other brands
Coldcough PD, Tusscough DHC

Related treatment guides