Drug interactions
Dextromethorphan + St john's wort
Severity: Major
Dextromethorphan and St john's wort: major interaction.
Last updated
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
St John's wort has serotonergic activity and combining it with dextromethorphan may result in serotonin syndrome. Symptoms include agitation, sweating, tremor, diarrhea and fever.
What this interaction means in plain words
Dextromethorphan and St john's wort 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 from inhibition of serotonin reuptake by St John's wort and dextromethorphan.
What to do
Avoid the combination and use a non-serotonergic antitussive. If both are taken, monitor for signs of serotonin toxicity.
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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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 Dextromethorphan with St john's wort?
MediHelp rates the interaction as major. Dextromethorphan and St john's wort 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. St John's wort has serotonergic activity and combining it with dextromethorphan may result in serotonin syndrome. Symptoms include agitation, sweating, tremor, diarrhea and fever.
How serious is the interaction between Dextromethorphan and St john's wort?
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 the combination and use a non-serotonergic antitussive. If both are taken, monitor for signs of serotonin toxicity.
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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