Drug interactions
Dextromethorphan + Ritonavir
Severity: Moderate
Dextromethorphan and Ritonavir: 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
Ritonavir inhibits CYP2D6 and CYP3A4 and can raise dextromethorphan concentrations. This may cause dizziness, sedation, confusion or serotonergic effects, particularly with repeated or high doses.
What this interaction means in plain words
Dextromethorphan and Ritonavir 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; Ritonavir belongs to Anti Virals.
Why it happens
Inhibition of CYP2D6 and CYP3A4 metabolism of dextromethorphan.
What to do
Use the lowest effective dextromethorphan dose and monitor for CNS and serotonergic adverse effects.
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 Ritonavir
- Alfuzosin + Ritonavir Contraindicated
- Amiodarone + Ritonavir Contraindicated
- Avanafil + Ritonavir Contraindicated
- Colchicine + Ritonavir Contraindicated
- Dronedarone + Ritonavir Contraindicated
- Eletriptan + Ritonavir Contraindicated
Frequently asked questions
Can I take Dextromethorphan with Ritonavir?
MediHelp rates the interaction as moderate. Dextromethorphan and Ritonavir 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. Ritonavir inhibits CYP2D6 and CYP3A4 and can raise dextromethorphan concentrations. This may cause dizziness, sedation, confusion or serotonergic effects, particularly with repeated or high doses.
How serious is the interaction between Dextromethorphan and Ritonavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Use the lowest effective dextromethorphan dose and monitor for CNS and serotonergic adverse effects.
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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