Drug interactions
Amoxapine + Dextromethorphan
Severity: Major
Amoxapine and Dextromethorphan: major interaction.
Last updated Sources: UK SmPC
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.
Summary
Both drugs have serotonergic activity, and amoxapine also inhibits CYP2D6 modestly, which can raise dextromethorphan exposure. The combination may increase the risk of serotonin syndrome, with agitation, tremor, hyperthermia and neuromuscular hyperactivity.
What this interaction means in plain words
Amoxapine and Dextromethorphan can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Additive serotonergic effects, with possible reduced CYP2D6 metabolism of dextromethorphan.
What to do
Avoid cough preparations containing dextromethorphan in patients taking amoxapine, or use a non-serotonergic antitussive. If used, counsel on symptoms of serotonin syndrome.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
- Benylin Dry Coughs 7.5mg / 5ml Syrup - SmPC sections 4.3/4.5 (class statement: psychotropics; "Dextromethorphan might exhibit additive CNS depressant effects when co-administered with alcohol, antihistamines, psychotropics, and other CNS depressant drugs.") — electronic medicines compendium (UK SmPC)
Other interactions of Dextromethorphan
- Dextromethorphan + Isocarboxazid Contraindicated
- Dextromethorphan + Linezolid Contraindicated
- Dextromethorphan + Phenelzine Contraindicated
- Dextromethorphan + Rasagiline Contraindicated
- Dextromethorphan + Safinamide Contraindicated
- Dextromethorphan + Selegiline Contraindicated
Frequently asked questions
Can I take Amoxapine with Dextromethorphan?
MediHelp rates the interaction as major. Amoxapine and Dextromethorphan can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs have serotonergic activity, and amoxapine also inhibits CYP2D6 modestly, which can raise dextromethorphan exposure. The combination may increase the risk of serotonin syndrome, with agitation, tremor, hyperthermia and neuromuscular hyperactivity.
How serious is the interaction between Amoxapine and Dextromethorphan?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid cough preparations containing dextromethorphan in patients taking amoxapine, or use a non-serotonergic antitussive. If used, counsel on symptoms of serotonin syndrome.
What other medicines interact with Dextromethorphan?
MediHelp also lists interactions of Dextromethorphan with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Dextromethorphan page.
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