Drug interactions
Dextromethorphan + Isoniazid
Severity: Moderate
Dextromethorphan and Isoniazid: moderate 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
Isoniazid has weak monoamine oxidase inhibiting activity, and with dextromethorphan this could theoretically increase serotonergic effects. Clinical cases are rare.
What this interaction means in plain words
Dextromethorphan and Isoniazid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Dextromethorphan belongs to Respiratory; Isoniazid belongs to Anti Bacterial.
Why it happens
Weak MAO inhibition by isoniazid may add to the serotonin reuptake inhibition of dextromethorphan.
What to do
Monitor for signs of serotonin toxicity such as agitation, tremor, sweating and hyperthermia. Prefer a non-dextromethorphan cough remedy if symptoms occur.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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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
Other interactions of Isoniazid
Frequently asked questions
Can I take Dextromethorphan with Isoniazid?
MediHelp rates the interaction as moderate. Dextromethorphan and Isoniazid can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Isoniazid has weak monoamine oxidase inhibiting activity, and with dextromethorphan this could theoretically increase serotonergic effects. Clinical cases are rare.
How serious is the interaction between Dextromethorphan and Isoniazid?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for signs of serotonin toxicity such as agitation, tremor, sweating and hyperthermia. Prefer a non-dextromethorphan cough remedy if symptoms occur.
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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