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Promethazine and dextromethorphan: Drug information

Promethazine and dextromethorphan: Drug information
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For additional information see "Promethazine and dextromethorphan: Patient drug information"

For abbreviations, symbols, and age group definitions show table
ALERT: US Boxed Warning
Respiratory depression - Pediatrics:

Promethazine should not be used in pediatric patients <2 years of age because of the potential for fatal respiratory depression.

Postmarketing cases of respiratory depression, including fatalities, have been reported with the use of promethazine in pediatric patients <2 years of age. A wide range of weight-based doses of promethazine have resulted in respiratory depression in these patients.

Caution should be exercised when administering promethazine to pediatric patients ≥2 years of age. It is recommended that the lowest effective dose of promethazine be used in pediatric patients ≥2 years of age and concomitant administration of other drugs with respiratory depressant effects be avoided.

Pharmacologic Category
  • Antitussive;
  • Histamine H1 Antagonist;
  • Histamine H1 Antagonist, First Generation;
  • Phenothiazine Derivative
Dosing: Adult
Cough and upper respiratory symptoms

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

Dosing: Kidney Impairment: Adult

There are no dosage adjustments provided in the manufacturer's labeling.

Dosing: Liver Impairment: Adult

There are no dosage adjustments provided in the manufacturer's labeling; use with caution (cholestatic jaundice has been reported with use).

Dosing: Older Adult

Avoid use (Ref).

Dosing: Pediatric
Cough and upper respiratory symptoms

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.

Dosing: Kidney Impairment: Pediatric

There are no dosage adjustments provided in the manufacturer’s labeling. See individual agents.

Dosing: Liver Impairment: Pediatric

Children ≥2 years and Adolescents: The manufacturer recommends to 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). See individual agents.

Adverse Reactions

See individual agents.

Contraindications

Hypersensitivity or idiosyncratic reaction to promethazine or other phenothiazines; coma; treatment of lower respiratory tract symptoms, including asthma; use with or within 14 days of monoamine oxidase inhibitor therapy; children <2 years of age.

Significant drug interactions exist, requiring dose/frequency adjustment or avoidance. Consult drug interactions database for more information.

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 GI motility, urinary retention, BPH, xerostomia, or visual problems.

• CNS depression: May cause CNS depression, which may impair physical or mental abilities; patients must be cautioned about performing tasks that require mental alertness (eg, operating machinery, driving).

• Extrapyramidal symptoms: May cause extrapyramidal symptoms, including pseudoparkinsonism, acute dystonic reactions, akathisia, and tardive dyskinesia.

• Neuroleptic malignant syndrome: Use may be associated with neuroleptic malignant syndrome; 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).

• Temperature regulation: Impaired core body temperature regulation may occur; use 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.

• 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: Avoid use in patients with compromised respiratory function or in patients at risk for respiratory failure (eg, chronic obstructive pulmonary disease, 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 that may lower seizure threshold.

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).

• Debilitated patients: Use dextromethorphan with caution in patients who are sedated, debilitated, or confined to a supine position.

• Pediatric: Antiemetics are not recommended for the treatment of uncomplicated vomiting in pediatric patients; limit use to prolonged vomiting of known etiology.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. Use dextromethorphan with caution in atopic children.

Other warnings/precautions:

• Abuse/Misuse: Health care providers should be alert to problems of abuse or misuse with dextromethorphan. Abuse can cause death, brain damage, seizure, loss of consciousness, and irregular heartbeat.

Dosage Forms: US

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)

Generic Equivalent Available: US

Yes

Pricing: US

Syrup (Promethazine-DM Oral)

6.25-15 mg/5 mL (per mL): $0.09

Disclaimer: A representative AWP (Average Wholesale Price) price or price range is provided as reference price only. A range is provided when more than one manufacturer's AWP price is available and uses the low and high price reported by the manufacturers to determine the range. The pricing data should be used for benchmarking purposes only, and as such should not be used alone to set or adjudicate any prices for reimbursement or purchasing functions or considered to be an exact price for a single product and/or manufacturer. Medi-Span expressly disclaims all warranties of any kind or nature, whether express or implied, and assumes no liability with respect to accuracy of price or price range data published in its solutions. In no event shall Medi-Span be liable for special, indirect, incidental, or consequential damages arising from use of price or price range data. Pricing data is updated monthly.

Administration: Adult

Oral: Measure and administer with an accurate measuring device (eg, dosing syringe, dosing spoon, dosing cup); do not use a household teaspoon (overdosage may occur).

Administration: Pediatric

Oral: Administer liquid formulation with an accurate measuring device; do not use a household teaspoon (overdosage may occur).

Use: Labeled Indications

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

Medication Safety Issues
Older Adult: High-risk medication:

Beers Criteria: Promethazine, a first-generation antihistamine, is identified in the Beers Criteria as a potentially inappropriate medication to be avoided in patients 65 years and older (independent of diagnosis or condition) due to its potent anticholinergic properties resulting in increased risk of confusion, dry mouth, constipation, and other anticholinergic effects or toxicity; use should also be avoided due to reduced clearance with advanced age and tolerance associated with use as a hypnotic. Exposure to concurrent anticholinergic drugs also increases risk of falls, delirium, and dementia; consider total anticholinergic burden when conducting medication reviews (Beers Criteria [AGS 2023]).

Pediatric patients: High-risk medication:

KIDs List: Dopamine antagonists, when used in pediatric patients <18 years of age, are identified on the Key Potentially Inappropriate Drugs in Pediatrics (KIDs) list; use should be avoided in infants and used with caution in children and adolescents due to risk of acute dystonia (dyskinesia), and with intravenous administration an increased risk of respiratory depression, extravasation, and death (strong recommendation; moderate quality of evidence) (PPA [Meyers 2020]).

Metabolism/Transport Effects

Refer to individual components.

Drug Interactions

Note: Interacting drugs may not be individually listed below if they are part of a group interaction (eg, individual drugs within “CYP3A4 Inducers [Strong]” are NOT listed). For a complete list of drug interactions by individual drug name and detailed management recommendations, use the drug interactions program by clicking on the “Launch drug interactions program” link above.

Acetylcholinesterase Inhibitors: May decrease therapeutic effects of Agents with Clinically Relevant Anticholinergic Effects. Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Acetylcholinesterase Inhibitors. Risk C: Monitor

Aclidinium: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid

Acrivastine: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Acrivastine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Agents with Clinically Relevant Anticholinergic Effects: May increase anticholinergic effects of Promethazine. Risk C: Monitor

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

Alcohol (Ethyl): CNS Depressants may increase CNS depressant effects of Alcohol (Ethyl). Risk C: Monitor

Alizapride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Amantadine: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Aminolevulinic Acid (Systemic): Photosensitizing Agents may increase photosensitizing effects of Aminolevulinic Acid (Systemic). Risk X: Avoid

Aminolevulinic Acid (Topical): Photosensitizing Agents may increase photosensitizing effects of Aminolevulinic Acid (Topical). Risk C: Monitor

Amisulpride (Oral): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Artemether and Lumefantrine: May increase serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk C: Monitor

Articaine: May increase CNS depressant effects of CNS Depressants. Management: Consider reducing the dose of articaine if possible when used in patients who are also receiving CNS depressants. Monitor for excessive CNS depressant effects with any combined use. Risk D: Consider Therapy Modification

Azelastine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Benperidol: Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Benperidol. Risk C: Monitor

Benperidol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Benztropine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Benztropine. Risk C: Monitor

Biperiden: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Biperiden. Risk C: Monitor

Blonanserin: CNS Depressants may increase CNS depressant effects of Blonanserin. Management: Use caution if coadministering blonanserin and CNS depressants; dose reduction of the other CNS depressant may be required. Strong CNS depressants should not be coadministered with blonanserin. Risk D: Consider Therapy Modification

Bornaprine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Bornaprine. Risk C: Monitor

Botulinum Toxin-Containing Products: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Brexanolone: CNS Depressants may increase CNS depressant effects of Brexanolone. Risk C: Monitor

Brimonidine (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Bromopride: May increase adverse/toxic effects of Promethazine. Risk X: Avoid

Bromperidol: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Buclizine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Buclizine. Risk C: Monitor

Buclizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Buprenorphine: CNS Depressants may increase CNS depressant effects 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. Risk D: Consider Therapy Modification

BusPIRone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Cannabinoid-Containing Products: Agents with Clinically Relevant Anticholinergic Effects may increase tachycardic effects of Cannabinoid-Containing Products. Risk C: Monitor

Cannabinoid-Containing Products: CNS Depressants may increase CNS depressant effects of Cannabinoid-Containing Products. Risk C: Monitor

Cetirizine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk D: Consider Therapy Modification

Chloral Hydrate/Chloral Betaine: CNS Depressants may increase CNS depressant effects of Chloral Hydrate/Chloral Betaine. Management: Consider alternatives to the use of chloral hydrate or chloral betaine and additional CNS depressants. If combined, consider a dose reduction of either agent and monitor closely for enhanced CNS depressive effects. Risk D: Consider Therapy Modification

Chlormethiazole: May increase CNS depressant effects 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. Risk D: Consider Therapy Modification

Chlorphenesin Carbamate: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor

Chlorprothixene: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Chlorprothixene. Risk C: Monitor

Cimetropium: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Cimetropium. Risk X: Avoid

CloZAPine: Agents with Clinically Relevant Anticholinergic Effects may increase constipating effects of CloZAPine. Management: Consider alternatives to this combination whenever possible. If combined, monitor closely for signs and symptoms of gastrointestinal hypomotility and consider prophylactic laxative treatment. Risk D: Consider Therapy Modification

CNS Depressants: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor

Cyclizine: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

CYP2D6 Inhibitors (Moderate): May increase serum concentration of Dextromethorphan. Risk C: Monitor

CYP2D6 Inhibitors (Strong): May increase serum concentration of Dextromethorphan. Risk C: Monitor

Dantrolene: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Daridorexant: May increase CNS depressant effects of CNS Depressants. Management: Dose reduction of daridorexant and/or any other CNS depressant may be necessary. Use of daridorexant with alcohol is not recommended, and the use of daridorexant with any other drug to treat insomnia is not recommended. Risk D: Consider Therapy Modification

Darifenacin: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Darifenacin. Risk C: Monitor

DexmedeTOMIDine: CNS Depressants may increase CNS depressant effects of DexmedeTOMIDine. Management: Monitor for increased CNS depression during coadministration of dexmedetomidine and CNS depressants, and consider dose reductions of either agent to avoid excessive CNS depression. Risk D: Consider Therapy Modification

Dicyclomine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Dicyclomine. Risk C: Monitor

Difelikefalin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Difenoxin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Dihydralazine: CNS Depressants may increase hypotensive effects of Dihydralazine. Risk C: Monitor

Dimethindene (Systemic): Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Dimethindene (Systemic). Risk C: Monitor

Dimethindene (Topical): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Disulfiram: May increase adverse/toxic effects of Products Containing Ethanol. Management: Do not use disulfiram with dosage forms that contain ethanol. Risk X: Avoid

Dothiepin: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Doxylamine: CNS Depressants may increase CNS depressant effects of Doxylamine. Risk C: Monitor

DroNABinol: Agents with Clinically Relevant Anticholinergic Effects may increase tachycardic effects of DroNABinol. Risk X: Avoid

DroPERidol: May increase CNS depressant effects of CNS Depressants. Management: Consider dose reductions of droperidol or of other CNS agents (eg, opioids, barbiturates) with concomitant use. Risk D: Consider Therapy Modification

Eluxadoline: Agents with Clinically Relevant Anticholinergic Effects may increase constipating effects of Eluxadoline. Risk X: Avoid

Emedastine (Systemic): May increase CNS depressant effects of CNS Depressants. Management: Consider avoiding this combination if possible. If required, monitor for excessive sedation or CNS depression, limit the dose and duration of combination therapy, and consider CNS depressant dose reductions. Risk C: Monitor

Entacapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

EPINEPHrine (Systemic): Promethazine may decrease vasoconstricting effects of EPINEPHrine (Systemic). Management: Avoid epinephrine and consider norepinephrine or phenylephrine when treating hypotension due to promethazine overdose. Consider alternative vasocontrictors in patients treated with promethazine. This combination may be indicated in anaphylaxis treatment. Risk D: Consider Therapy Modification

Esketamine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Fesoterodine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Fesoterodine. Risk C: Monitor

Flunarizine: CNS Depressants may increase CNS depressant effects of Flunarizine. Risk X: Avoid

Flunitrazepam: CNS Depressants may increase CNS depressant effects of Flunitrazepam. Management: Reduce the dose of CNS depressants when combined with flunitrazepam and monitor patients for evidence of CNS depression (eg, sedation, respiratory depression). Use non-CNS depressant alternatives when available. Risk D: Consider Therapy Modification

FluPHENAZine: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Gastrointestinal Agents (Prokinetic): Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Gastrointestinal Agents (Prokinetic). Risk C: Monitor

Gepotidacin: May decrease anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Glucagon: Agents with Clinically Relevant Anticholinergic Effects may increase adverse/toxic effects of Glucagon. Specifically, the risk of gastrointestinal adverse effects may be increased. Risk C: Monitor

Glycopyrrolate (Oral Inhalation): Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Glycopyrrolate (Oral Inhalation). Risk X: Avoid

Glycopyrrolate (Systemic): Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Glycopyrrolate (Systemic). Risk C: Monitor

Glycopyrronium (Topical): May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid

Haloperidol: Promethazine may increase anticholinergic effects of Haloperidol. Promethazine may increase CNS depressant effects of Haloperidol. Promethazine may increase serum concentration of Haloperidol. Risk C: Monitor

HydrOXYzine: May increase CNS depressant effects of CNS Depressants. Management: Consider a decrease in the CNS depressant dose, as appropriate, when used together with hydroxyzine. Increase monitoring of signs/symptoms of CNS depression in any patient receiving hydroxyzine together with another CNS depressant. Risk D: Consider Therapy Modification

Ipratropium (Nasal): May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Ipratropium (Oral Inhalation): May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid

Itopride: Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Itopride. Risk C: Monitor

Ixabepilone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Kava Kava: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Ketotifen (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Kratom: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Lemborexant: May increase CNS depressant effects 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. Risk D: Consider Therapy Modification

Levocetirizine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Levosulpiride: Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Levosulpiride. Risk X: Avoid

Lisuride: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Lofepramine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Lofexidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Loxapine: CNS Depressants may increase CNS depressant effects of Loxapine. Management: Consider reducing the dose of CNS depressants administered concomitantly with loxapine due to an increased risk of respiratory depression, sedation, hypotension, and syncope. Risk D: Consider Therapy Modification

Magnesium Sulfate: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Maprotiline: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Maprotiline. Risk C: Monitor

Mavorixafor: May increase serum concentration of CYP2D6 Substrates (High risk with Inhibitors). Risk X: Avoid

Melitracen [INT]: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Melperone: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Memantine: NMDA Receptor Antagonists may increase adverse/toxic effects of Memantine. Risk C: Monitor

Mequitazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Metergoline: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Methotrimeprazine: May increase CNS depressant effects of Products Containing Ethanol. Management: Avoid products containing alcohol in patients treated with methotrimeprazine. Risk X: Avoid

Methoxsalen (Systemic): Photosensitizing Agents may increase photosensitizing effects of Methoxsalen (Systemic). Risk C: Monitor

Methoxyflurane: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Methscopolamine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Methscopolamine. Risk C: Monitor

Metoclopramide: May increase adverse/toxic effects of Promethazine. Risk X: Avoid

MetroNIDAZOLE (Systemic): May increase adverse/toxic effects of Products Containing Ethanol. A disulfiram-like reaction may occur. Risk X: Avoid

MetroNIDAZOLE (Topical): May increase adverse/toxic effects of Products Containing Ethanol. A disulfiram-like reaction may occur. Risk C: Monitor

MetyroSINE: May increase adverse/toxic effects of Promethazine. Specifically, the risk for extrapyramidal symptoms and excessive sedation may be increased. Risk C: Monitor

Minocycline (Systemic): May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Mirabegron: Agents with Clinically Relevant Anticholinergic Effects may increase adverse/toxic effects of Mirabegron. Risk C: Monitor

Monoamine Oxidase Inhibitors: Dextromethorphan may increase serotonergic effects of Monoamine Oxidase Inhibitors. This may cause serotonin syndrome. Risk X: Avoid

Moxonidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Nabilone: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Nalfurafine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Nitroglycerin: Agents with Clinically Relevant Anticholinergic Effects may decrease absorption of Nitroglycerin. Specifically, anticholinergic agents may decrease the dissolution of sublingual nitroglycerin tablets, possibly impairing or slowing nitroglycerin absorption. Risk C: Monitor

Noscapine: CNS Depressants may increase adverse/toxic effects of Noscapine. Risk X: Avoid

OLANZapine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of OLANZapine. Risk C: Monitor

Olopatadine (Nasal): May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Opicapone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Opioid Agonists: CNS Depressants may increase CNS depressant effects 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. Risk D: Consider Therapy Modification

Opipramol: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Opipramol: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Orphenadrine: CNS Depressants may increase CNS depressant effects of Orphenadrine. Risk X: Avoid

Oxatomide: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid

Oxomemazine: May increase CNS depressant effects of CNS Depressants. Risk X: Avoid

Oxybate Salt Products: CNS Depressants may increase CNS depressant effects of Oxybate Salt Products. Management: Consider alternatives to this combination when possible. If combined, dose reduction or discontinuation of one or more CNS depressants (including the oxybate salt product) should be considered. Interrupt oxybate salt treatment during short-term opioid use Risk D: Consider Therapy Modification

OxyBUTYnin: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of OxyBUTYnin. Risk C: Monitor

OxyCODONE: CNS Depressants may increase CNS depressant effects 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. Risk D: Consider Therapy Modification

Paliperidone: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Paraldehyde: CNS Depressants may increase CNS depressant effects of Paraldehyde. Risk X: Avoid

Parecoxib: May increase serum concentration of Dextromethorphan. Risk C: Monitor

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

Perampanel: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Perazine: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Periciazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Perphenazine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Perphenazine. Risk C: Monitor

Pipamperone: May increase adverse/toxic effects of CNS Depressants. Risk C: Monitor

Piribedil: CNS Depressants may increase CNS depressant effects of Piribedil. Risk C: Monitor

Pitolisant: Promethazine may decrease therapeutic effects of Pitolisant. Risk X: Avoid

Pizotifen: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Porfimer: Photosensitizing Agents may increase photosensitizing effects of Porfimer. Risk X: Avoid

Potassium Chloride: Agents with Clinically Relevant Anticholinergic Effects may increase ulcerogenic effects of Potassium Chloride. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium chloride. Risk X: Avoid

Potassium Citrate: Agents with Clinically Relevant Anticholinergic Effects may increase ulcerogenic effects of Potassium Citrate. Management: Patients on drugs with substantial anticholinergic effects should avoid using any solid oral dosage form of potassium citrate. Risk X: Avoid

Pramipexole: CNS Depressants may increase sedative effects of Pramipexole. Risk C: Monitor

Pramlintide: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. These effects are specific to the GI tract. Risk X: Avoid

Procarbazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Propantheline: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Propantheline. Risk C: Monitor

Propiverine: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

QuiNIDine: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk C: Monitor

Ramosetron: Agents with Clinically Relevant Anticholinergic Effects may increase constipating effects of Ramosetron. Risk C: Monitor

Revefenacin: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Revefenacin. Risk X: Avoid

Rilmenidine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Rivastigmine: Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Rivastigmine. Rivastigmine may decrease therapeutic effects of Agents with Clinically Relevant Anticholinergic Effects. Management: Use of rivastigmine with an anticholinergic agent is not recommended unless clinically necessary. If the combination is necessary, monitor for reduced anticholinergic effects. Risk D: Consider Therapy Modification

Ropeginterferon Alfa-2b: CNS Depressants may increase adverse/toxic effects of Ropeginterferon Alfa-2b. Specifically, the risk of neuropsychiatric adverse effects may be increased. Management: Avoid coadministration of ropeginterferon alfa-2b and other CNS depressants. If this combination cannot be avoided, monitor patients for neuropsychiatric adverse effects (eg, depression, suicidal ideation, aggression, mania). Risk D: Consider Therapy Modification

ROPINIRole: CNS Depressants may increase sedative effects of ROPINIRole. Risk C: Monitor

Rotigotine: CNS Depressants may increase sedative effects of Rotigotine. Risk C: Monitor

Scopolamine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Scopolamine. Risk C: Monitor

Secnidazole: Products Containing Ethanol may increase adverse/toxic effects of Secnidazole. Risk X: Avoid

Secretin: Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Secretin. Management: Avoid concomitant use of anticholinergic agents and secretin. Discontinue anticholinergic agents at least 5 half-lives prior to administration of secretin. Risk D: Consider Therapy Modification

Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors): Dextromethorphan may increase serotonergic effects of Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors). This could result in serotonin syndrome. Selective Serotonin Reuptake Inhibitors (Strong CYP2D6 Inhibitors) may increase serum concentration of Dextromethorphan. Management: Consider alternatives to this drug combination. The dose of dextromethorphan/bupropion product should not exceed 1 tablet once daily. Monitor for signs and symptoms of serotonin syndrome/serotonin toxicity. Risk D: Consider Therapy Modification

Serotonergic Agents (High Risk): Dextromethorphan may increase serotonergic effects 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. Risk C: Monitor

Sofpironium: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Sofpironium. Risk X: Avoid

Suvorexant: CNS Depressants may increase CNS depressant effects 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. Risk D: Consider Therapy Modification

Thalidomide: CNS Depressants may increase CNS depressant effects of Thalidomide. Risk X: Avoid

Thiazide and Thiazide-Like Diuretics: Agents with Clinically Relevant Anticholinergic Effects may increase serum concentration of Thiazide and Thiazide-Like Diuretics. Risk C: Monitor

Thiothixene: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Thiothixene. Risk C: Monitor

Tiapride: Agents with Clinically Relevant Anticholinergic Effects may decrease therapeutic effects of Tiapride. Risk C: Monitor

Tiotropium: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Tiotropium. Risk X: Avoid

Tolterodine: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Tolterodine. Risk C: Monitor

Topiramate: Agents with Clinically Relevant Anticholinergic Effects may increase adverse/toxic effects of Topiramate. Risk C: Monitor

Tranylcypromine: May increase anticholinergic effects of Antihistamines, First Generation. Risk X: Avoid

Trimeprazine: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Trimethobenzamide: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Trimethobenzamide. Risk C: Monitor

Trospium: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Trospium. Risk C: Monitor

Umeclidinium: May increase anticholinergic effects of Agents with Clinically Relevant Anticholinergic Effects. Risk X: Avoid

Valerian: May increase CNS depressant effects of CNS Depressants. Risk C: Monitor

Verteporfin: Photosensitizing Agents may increase photosensitizing effects of Verteporfin. Risk C: Monitor

Zolpidem: CNS Depressants may increase CNS depressant effects 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. Risk D: Consider Therapy Modification

Zuclopenthixol: Agents with Clinically Relevant Anticholinergic Effects may increase anticholinergic effects of Zuclopenthixol. Risk C: Monitor

Zuranolone: May increase CNS depressant effects of CNS Depressants. Management: Consider alternatives to the use of zuranolone with other CNS depressants or alcohol. If combined, consider a zuranolone dose reduction and monitor patients closely for increased CNS depressant effects. Risk D: Consider Therapy Modification

Pregnancy Considerations

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

Breastfeeding Considerations

Refer to individual monographs.

Dietary Considerations

Increase dietary intake of riboflavin.

Pharmacokinetics (Adult Data Unless Noted)

See individual agents.

Brand Names: International
International Brand Names by Country
For country code abbreviations (show table)

  • (CO) Colombia: Kataronex;
  • (HK) Hong Kong: Axcel dextrozine;
  • (ID) Indonesia: Neo davenol;
  • (IN) India: Neozeet | Tussdex | Tussdex-a;
  • (MY) Malaysia: Metofen compound;
  • (PR) Puerto Rico: Phen-Tuss DM | Phenergan dm | Prometh with dextromethorphan | Promethazine dm | Promethazine hydrochloride and Dextromethorphan hydrobromide | Promethazine w/ dextromethorphan;
  • (TH) Thailand: Dextrodyl
  1. 2023 American Geriatrics Society Beers Criteria Update Expert Panel. American Geriatrics Society 2023 updated AGS Beers Criteria for potentially inappropriate medication use in older adults. J Am Geriatr Soc. 2023;71(7):2052-2081. doi:10.1111/jgs.18372 [PubMed 37139824]
  2. Abduljalil K, Frank D, Gaedigk A, et al. Assessment of activity levels for CYP2D6*1, CYP2D6*2, and CYP2D6*41 genes by population pharmacokinetics of dextromethorphan. Clin Pharmacol Ther. 2010;88(5):643-651. doi: 10.1038/clpt.2010.137. [PubMed 20881950]
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  5. Promethazine DM (promethazine and dextromethorphan) [prescribing information]. Monmouth Junction, NJ: Tris Pharma; July 2021.
  6. Sager JE, Lutz JD, Foti RS, et al. Fluoxetine- and norfluoxetine-mediated complex drug-drug interactions: in vitro to in vivo correlation of effects on CYP2D6, CYP2C19, and CYP3A4. Clin Pharmacol Ther. 2014;95(6):653-662. doi: 10.1038/clpt.2014.50. [PubMed 24569517]
  7. Zhou SF. Polymorphism of human cytochrome P450 2D6 and its clinical significance: part II. Clin Pharmacokinet. 2009;48(12):761-804. doi:10.2165/11318070. [PubMed 19902987]
Topic 10071 Version 281.0