Promethazine and Dextromethorphan

Dosage Forms

Excipient information presented when available (limited, particularly for generics); consult specific product labeling.

Syrup: Promethazine hydrochloride 6.25 mg and dextromethorphan hydrobromide 15 mg per 5 mL (120 mL, 480 mL)

Use: Labeled Indications

Temporary relief of coughs and upper respiratory symptoms associated with allergy or the common cold

Contraindications

Hypersensitivity to promethazine, dextromethorphan, or any component of the formulation (cross-reactivity between phenothiazines may occur); treatment of lower respiratory tract symptoms, including asthma; use with or within 14 days of MAO inhibitor therapy

Dosage and Administration

Dosing: Adult

Cough and upper respiratory symptoms: Oral: 5 mL every 4 to 6 hours; maximum: 30 mL in 24 hours

Dosing: Geriatric

Avoid use (Beers Criteria [AGS 2019]).

Dosing: Pediatric

Cough and upper respiratory symptoms: Oral: Children:

2 to <6 years: 1.25 to 2.5 mL every 4 to 6 hours; maximum: 10 mL in 24 hours

6 to <12 years: 2.5 to 5 mL every 4 to 6 hours; maximum: 20 mL in 24 hours

≥12 years and Adolescents: Refer to adult dosing

Dietary Considerations

Increase dietary intake of riboflavin.

Drug Interactions

Abiraterone Acetate: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Management: Avoid concurrent use of abiraterone with CYP2D6 substrates that have a narrow therapeutic index whenever possible. When concurrent use is not avoidable, monitor patients closely for signs/symptoms of toxicity. Consider therapy modification

Acetylcholinesterase Inhibitors: May diminish the therapeutic effect of Anticholinergic Agents. Anticholinergic Agents may diminish the therapeutic effect of Acetylcholinesterase Inhibitors. Monitor therapy

Aclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Ajmaline: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Monitor therapy

Alizapride: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Amantadine: May enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy

Aminolevulinic Acid (Systemic): Photosensitizing Agents may enhance the photosensitizing effect of Aminolevulinic Acid (Systemic). Avoid combination

Aminolevulinic Acid (Topical): Photosensitizing Agents may enhance the photosensitizing effect of Aminolevulinic Acid (Topical). Monitor therapy

Anticholinergic Agents: May enhance the adverse/toxic effect of other Anticholinergic Agents. Monitor therapy

Asunaprevir: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Consider therapy modification

Azelastine (Nasal): CNS Depressants may enhance the CNS depressant effect of Azelastine (Nasal). Avoid combination

Blonanserin: CNS Depressants may enhance the CNS depressant effect of Blonanserin. Consider therapy modification

Botulinum Toxin-Containing Products: May enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy

Brexanolone: CNS Depressants may enhance the CNS depressant effect of Brexanolone. Monitor therapy

Brimonidine (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Bromopride: May enhance the adverse/toxic effect of Promethazine. Avoid combination

Bromperidol: May enhance the CNS depressant effect of CNS Depressants. Avoid combination

Buprenorphine: CNS Depressants may enhance the CNS depressant effect of Buprenorphine. Management: Consider reduced doses of other CNS depressants, and avoiding such drugs in patients at high risk of buprenorphine overuse/self-injection. Initiate buprenorphine at lower doses in patients already receiving CNS depressants. Consider therapy modification

Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Cannabis: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Chloral Betaine: May enhance the adverse/toxic effect of Anticholinergic Agents. Monitor therapy

Chlormethiazole: May enhance the CNS depressant effect of CNS Depressants. Management: Monitor closely for evidence of excessive CNS depression. The chlormethiazole labeling states that an appropriately reduced dose should be used if such a combination must be used. Consider therapy modification

Chlorphenesin Carbamate: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Cimetropium: Anticholinergic Agents may enhance the anticholinergic effect of Cimetropium. Avoid combination

CloBAZam: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Monitor therapy

Cobicistat: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

CYP2D6 Inhibitors (Moderate): May decrease the metabolism of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

CYP2D6 Inhibitors (Strong): May decrease the metabolism of CYP2D6 Substrates (High risk with Inhibitors). Consider therapy modification

Dacomitinib: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Management: Avoid concurrent use of dacomitinib with CYP2D6 subtrates that have a narrow therapeutic index. Consider therapy modification

Darunavir: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Dimethindene (Topical): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Doxylamine: May enhance the CNS depressant effect of CNS Depressants. Management: The manufacturer of Diclegis (doxylamine/pyridoxine), intended for use in pregnancy, specifically states that use with other CNS depressants is not recommended. Monitor therapy

Dronabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Droperidol: May enhance the CNS depressant effect of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Consider therapy modification

Eluxadoline: Anticholinergic Agents may enhance the constipating effect of Eluxadoline. Avoid combination

EPINEPHrine (Nasal): Promethazine may diminish the vasoconstricting effect of EPINEPHrine (Nasal). Monitor therapy

EPINEPHrine (Oral Inhalation): Promethazine may diminish the therapeutic effect of EPINEPHrine (Oral Inhalation). Monitor therapy

Epinephrine (Racemic): Promethazine may diminish the vasoconstricting effect of Epinephrine (Racemic). Management: Monitor for diminished vasoconstrictive effects of racemic epinephrine (e.g., diminished efficacy when used for gingival retraction). This interaction is likely of less concern in patients receiving epinephrine for other purposes (e.g., bronchodilation). Monitor therapy

EPINEPHrine (Systemic): Promethazine may diminish the vasoconstricting effect of EPINEPHrine (Systemic). Management: When vasoconstrictive effects are desired in patients receiving promethazine, consider alternatives to epinephrine. Consider use of norepinephrine or phenylephrine, and avoid epinephrine, when treating hypotension associated with promethazine overdose. Consider therapy modification

Esketamine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Flunitrazepam: CNS Depressants may enhance the CNS depressant effect of Flunitrazepam. Consider therapy modification

Gastrointestinal Agents (Prokinetic): Anticholinergic Agents may diminish the therapeutic effect of Gastrointestinal Agents (Prokinetic). Monitor therapy

Glucagon: Anticholinergic Agents may enhance the adverse/toxic effect of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Monitor therapy

Glycopyrrolate (Oral Inhalation): Anticholinergic Agents may enhance the anticholinergic effect of Glycopyrrolate (Oral Inhalation). Avoid combination

Glycopyrronium (Topical): May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Haloperidol: Promethazine may enhance the anticholinergic effect of Haloperidol. Promethazine may enhance the CNS depressant effect of Haloperidol. Promethazine may increase the serum concentration of Haloperidol. Monitor therapy

HYDROcodone: CNS Depressants may enhance the CNS depressant effect of HYDROcodone. Management: Avoid concomitant use of hydrocodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification

HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Imatinib: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Ipratropium (Oral Inhalation): May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Itopride: Anticholinergic Agents may diminish the therapeutic effect of Itopride. Monitor therapy

Kava Kava: May enhance the adverse/toxic effect of CNS Depressants. Monitor therapy

Lemborexant: May enhance the CNS depressant effect of CNS Depressants. Management: Dosage adjustments of lemborexant and of concomitant CNS depressants may be necessary when administered together because of potentially additive CNS depressant effects. Close monitoring for CNS depressant effects is necessary. Consider therapy modification

Levosulpiride: Anticholinergic Agents may diminish the therapeutic effect of Levosulpiride. Avoid combination

Lofexidine: May enhance the CNS depressant effect of CNS Depressants. Management: Drugs listed as exceptions to this monograph are discussed in further detail in separate drug interaction monographs. Monitor therapy

Lumefantrine: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Magnesium Sulfate: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Memantine: NMDA Receptor Antagonists may enhance the adverse/toxic effect of Memantine. Monitor therapy

Methotrimeprazine: CNS Depressants may enhance the CNS depressant effect of Methotrimeprazine. Methotrimeprazine may enhance the CNS depressant effect of CNS Depressants. Management: Reduce adult dose of CNS depressant agents by 50% with initiation of concomitant methotrimeprazine therapy. Further CNS depressant dosage adjustments should be initiated only after clinically effective methotrimeprazine dose is established. Consider therapy modification

Metoclopramide: May enhance the adverse/toxic effect of Promethazine. Avoid combination

MetyroSINE: May enhance the adverse/toxic effect of Promethazine. Monitor therapy

Mianserin: May enhance the anticholinergic effect of Anticholinergic Agents. Monitor therapy

Minocycline (Systemic): May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Mirabegron: Anticholinergic Agents may enhance the adverse/toxic effect of Mirabegron. Monitor therapy

Monoamine Oxidase Inhibitors: May enhance the serotonergic effect of Dextromethorphan. This may cause serotonin syndrome. Avoid combination

Nabilone: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Nitroglycerin: Anticholinergic Agents may decrease the absorption of Nitroglycerin. Specifically, anticholinergic agents may decrease the dissolution of sublingual nitroglycerin tablets, possibly impairing or slowing nitroglycerin absorption. Monitor therapy

Opioid Agonists: CNS Depressants may enhance the CNS depressant effect of Opioid Agonists. Management: Avoid concomitant use of opioid agonists and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification

Orphenadrine: CNS Depressants may enhance the CNS depressant effect of Orphenadrine. Avoid combination

Oxatomide: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Oxomemazine: May enhance the CNS depressant effect of CNS Depressants. Avoid combination

OxyCODONE: CNS Depressants may enhance the CNS depressant effect of OxyCODONE. Management: Avoid concomitant use of oxycodone and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification

Panobinostat: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Paraldehyde: CNS Depressants may enhance the CNS depressant effect of Paraldehyde. Avoid combination

Parecoxib: May increase the serum concentration of Dextromethorphan. Monitor therapy

Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Peginterferon Alfa-2b may increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Perampanel: May enhance the CNS depressant effect of CNS Depressants. Management: Patients taking perampanel with any other drug that has CNS depressant activities should avoid complex and high-risk activities, particularly those such as driving that require alertness and coordination, until they have experience using the combination. Consider therapy modification

Perhexiline: CYP2D6 Substrates (High risk with Inhibitors) may increase the serum concentration of Perhexiline. Perhexiline may increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Piribedil: CNS Depressants may enhance the CNS depressant effect of Piribedil. Monitor therapy

Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Monitor therapy

Potassium Chloride: Anticholinergic Agents may enhance the ulcerogenic effect of Potassium Chloride. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium chloride. Avoid combination

Potassium Citrate: Anticholinergic Agents may enhance the ulcerogenic effect of Potassium Citrate. Avoid combination

Pramipexole: CNS Depressants may enhance the sedative effect of Pramipexole. Monitor therapy

Pramlintide: May enhance the anticholinergic effect of Anticholinergic Agents. These effects are specific to the GI tract. Consider therapy modification

QuiNIDine: May increase the serum concentration of Dextromethorphan. Management: Avoid concurrent use of these agents when possible, unless the increased psychoactive effects of dextromethorphan are desired. Since codeine activation is also inhibited by quinidine, codeine is unlikely to be suitable as an alternative antitussive. Consider therapy modification

QuiNINE: May increase the serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Monitor therapy

Ramosetron: Anticholinergic Agents may enhance the constipating effect of Ramosetron. Monitor therapy

Revefenacin: Anticholinergic Agents may enhance the anticholinergic effect of Revefenacin. Avoid combination

ROPINIRole: CNS Depressants may enhance the sedative effect of ROPINIRole. Monitor therapy

Rotigotine: CNS Depressants may enhance the sedative effect of Rotigotine. Monitor therapy

Rufinamide: May enhance the adverse/toxic effect of CNS Depressants. Specifically, sleepiness and dizziness may be enhanced. Monitor therapy

Secretin: Anticholinergic Agents may diminish the therapeutic effect of Secretin. Management: Avoid concomitant use of anticholinergic agents and secretin. Discontinue anticholinergic agents at least 5 half-lives prior to administration of secretin. Consider therapy modification

Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors): Dextromethorphan may enhance the serotonergic effect of Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors). This could result in serotonin syndrome. Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors) may increase the serum concentration of Dextromethorphan. Management: Consider alternatives to this drug combination. If combined, monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes). Consider therapy modification

Serotonergic Agents (High Risk): Dextromethorphan may enhance the serotonergic effect of Serotonergic Agents (High Risk). This could result in serotonin syndrome. Management: Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity (eg, hyperreflexia, clonus, hyperthermia, diaphoresis, tremor, autonomic instability, mental status changes) when these agents are combined. Exceptions: FLUoxetine; Isocarboxazid; Linezolid; Methylene Blue; Moclobemide; PARoxetine; Phenelzine; Tranylcypromine. Monitor therapy

Sodium Oxybate: May enhance the CNS depressant effect of CNS Depressants. Management: Consider alternatives to combined use. When combined use is needed, consider minimizing doses of one or more drugs. Use of sodium oxybate with alcohol or sedative hypnotics is contraindicated. Consider therapy modification

Suvorexant: CNS Depressants may enhance the CNS depressant effect of Suvorexant. Management: Dose reduction of suvorexant and/or any other CNS depressant may be necessary. Use of suvorexant with alcohol is not recommended, and the use of suvorexant with any other drug to treat insomnia is not recommended. Consider therapy modification

Tapentadol: May enhance the CNS depressant effect of CNS Depressants. Management: Avoid concomitant use of tapentadol and benzodiazepines or other CNS depressants when possible. These agents should only be combined if alternative treatment options are inadequate. If combined, limit the dosages and duration of each drug. Consider therapy modification

Tetrahydrocannabinol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Tetrahydrocannabinol and Cannabidiol: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Thalidomide: CNS Depressants may enhance the CNS depressant effect of Thalidomide. Avoid combination

Thiazide and Thiazide-Like Diuretics: Anticholinergic Agents may increase the serum concentration of Thiazide and Thiazide-Like Diuretics. Monitor therapy

Tiotropium: Anticholinergic Agents may enhance the anticholinergic effect of Tiotropium. Avoid combination

Tipranavir: May increase the serum concentration of Dextromethorphan. Management: Consider avoiding dextromethorphan in patients taking tipranavir. If combined, monitor closely for increased dextromethorphan effects/toxicities. Consider therapy modification

Topiramate: Anticholinergic Agents may enhance the adverse/toxic effect of Topiramate. Monitor therapy

Trimeprazine: May enhance the CNS depressant effect of CNS Depressants. Monitor therapy

Umeclidinium: May enhance the anticholinergic effect of Anticholinergic Agents. Avoid combination

Verteporfin: Photosensitizing Agents may enhance the photosensitizing effect of Verteporfin. Monitor therapy

Zolpidem: CNS Depressants may enhance the CNS depressant effect of Zolpidem. Management: Reduce the Intermezzo brand sublingual zolpidem adult dose to 1.75 mg for men who are also receiving other CNS depressants. No such dose change is recommended for women. Avoid use with other CNS depressants at bedtime; avoid use with alcohol. Consider therapy modification

Test Interactions

See individual agents.

Adverse Reactions

See individual agents.

Warnings/Precautions

Concerns related to adverse effects:

• Altered cardiac conduction: May alter cardiac conduction (life-threatening arrhythmias have occurred with therapeutic doses of phenothiazines).
• Anticholinergic effects: Phenothiazines may cause anticholinergic effects (constipation, xerostomia, blurred vision, urinary retention); therefore, they should be used with caution in patients with decreased gastrointestinal motility, urinary retention, BPH, xerostomia, or visual problems.
• Extrapyramidal symptoms: May cause extrapyramidal symptoms, including pseudoparkinsonism, acute dystonic reactions, akathisia, and tardive dyskinesia.
• Neuroleptic malignant syndrome (NMS): Use may be associated with NMS; monitor for mental status changes, fever, muscle rigidity and/or autonomic instability.
• Orthostatic hypotension: May cause orthostatic hypotension; use with caution in patients at risk of this effect or in those who would not tolerate transient hypotensive episodes (cerebrovascular disease, cardiovascular disease, hypovolemia, or concurrent medication use which may predispose to hypotension/bradycardia).
• Sedation: May be sedating, use with caution in disorders where CNS depression is a feature; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).
• Temperature regulation: Impaired core body temperature regulation may occur; caution with strenuous exercise, heat exposure, dehydration, and concomitant medication possessing anticholinergic effects.

Disease-related concerns:

• Bone marrow suppression: Use with caution in patients with bone marrow suppression; leukopenia and agranulocytosis have been reported.
• Cardiovascular disease: Use with caution in patients with severe cardiovascular disease.
• Glaucoma: Use with caution in patients with narrow-angle glaucoma; condition may be exacerbated by cholinergic blockade. Screening is recommended.
• Hepatic impairment: Use with caution in patients with hepatic impairment; cholestatic jaundice has been reported with promethazine use. Avoid use in pediatric patients with signs and symptoms of hepatic disease (extrapyramidal symptoms caused by promethazine may be confused with CNS signs of hepatic disease).
• Myasthenia gravis: Use with caution in patients with myasthenia gravis; condition may be exacerbated by cholinergic blockade.
• Parkinson disease: Use with caution in patients with Parkinson disease; may have increased risk of tardive dyskinesia.
• Respiratory disease: Use with caution in patients with severe respiratory disease (asthma, COPD, sleep apnea); may lead to potentially fatal respiratory depression.
• Seizures: Use with caution in patients at risk of seizures, including those with a history of seizures, head trauma, brain damage, alcoholism, or concurrent therapy with medications which may lower seizure threshold.

Concurrent drug therapy issues:

• Antiemetic effects: May mask toxicity of other drugs or conditions (eg, intestinal obstruction, Reye's syndrome, brain tumor) due to antiemetic effects.
• Sedatives: Effects may be potentiated when used with other sedative drugs or ethanol.

Special populations:

• CYP2D6 poor metabolizers: Dextromethorphan is metabolized by hepatic CYP2D6. Poor metabolizers of CYP2D6 may have exaggerated or prolonged effects of dextromethorphan. Increased risk may be seen with concomitant use of potent CYP2D6 inhibitors; use with caution (Abduljalil 2010; Jurica 2012; Sager 2014; Zhou 2009).
• Pediatric: [U.S. Boxed Warning]: Safety and efficacy of this combination have not been established in children <2 years of age (use of promethazine is contraindicated). In children ≥2 years, use the lowest possible dose; other drugs with respiratory depressant effects should be avoided. Avoid use in children who may have Reye syndrome or hepatic disease as adverse reactions caused by promethazine may be confused with signs of primary disease.

Pregnancy

Pregnancy Risk Factor

C

Pregnancy Considerations

Reproduction studies have not been conducted with this combination. Refer to individual monographs.

Patient Education

• Discuss specific use of drug and side effects with patient as it relates to treatment. (HCAHPS: During this hospital stay, were you given any medicine that you had not taken before? Before giving you any new medicine, how often did hospital staff tell you what the medicine was for? How often did hospital staff describe possible side effects in a way you could understand?)
• Patient may experience fatigue, dry mouth, vomiting, or nausea. Have patient report immediately to prescriber signs of infection, slow heartbeat, difficulty breathing, slow breathing, shallow breathing, noisy breathing, severe dizziness, passing out, severe constipation, unable to pass urine, loss of strength and energy, abnormal movements, twitching, change in balance, dysphagia, difficulty speaking, sensing things that seem real but are not, mood changes, noise or ringing in the ears, seizures, bruising, bleeding, vision changes, severe anxiety, trouble sleeping, yellow skin, or signs of neuroleptic malignant syndrome (fever, muscle cramps or stiffness, dizziness, very bad headache, confusion, change in thinking, fast heartbeat, abnormal heartbeat, or sweating a lot) (HCAHPS).
• Educate patient about signs of a significant reaction (eg, wheezing; chest tightness; fever; itching; bad cough; blue skin color; seizures; or swelling of face, lips, tongue, or throat). Note: This is not a comprehensive list of all side effects. Patient should consult prescriber for additional questions.

Intended Use and Disclaimer: Should not be printed and given to patients. This information is intended to serve as a concise initial reference for healthcare professionals to use when discussing medications with a patient. You must ultimately rely on your own discretion, experience and judgment in diagnosing, treating and advising patients.