Drug interactions
Cimetidine + Dextromethorphan
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Overview
Cimetidine can increase dextromethorphan exposure, potentially enhancing CNS effects (e.g., dizziness, sedation).
Mechanism of action
Pharmacokinetic: Cimetidine inhibits CYP2D6 and CYP3A4, reducing dextromethorphan metabolism to dextrorphan and other metabolites.
Clinical management
Use lowest effective dextromethorphan dose; monitor for enhanced CNS effects. Consider alternative antitussive if problematic.
Drug reference
References
- Dextromethorphan: Drug Information — Lexicomp
- Cimetidine: Drug Information — Lexicomp
Frequently asked questions
Can I take Cimetidine with Dextromethorphan?
The interaction is rated: Moderate. Cimetidine can increase dextromethorphan exposure, potentially enhancing CNS effects (e.g., dizziness, sedation).
How serious is the interaction between Cimetidine and Dextromethorphan?
The interaction is rated: Moderate. Evidence level: Moderate.
How is the interaction between Cimetidine and Dextromethorphan managed?
Use lowest effective dextromethorphan dose; monitor for enhanced CNS effects. Consider alternative antitussive if problematic.
Why do Cimetidine and Dextromethorphan interact?
Pharmacokinetic: Cimetidine inhibits CYP2D6 and CYP3A4, reducing dextromethorphan metabolism to dextrorphan and other metabolites.
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