Drug interactions
Methadone + Ritonavir
Severity: Moderate
Methadone 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 has mixed effects on methadone, and in practice usually lowers methadone concentrations, which can cause withdrawal. Methadone dose needs may rise, especially with boosted protease inhibitor regimens.
What this interaction means in plain words
Methadone 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.
Methadone belongs to Musculoskeletal; Ritonavir belongs to Anti Virals.
Why it happens
Ritonavir induces methadone metabolism while also inhibiting CYP3A4, with the net effect often a reduction in exposure.
What to do
Monitor for withdrawal or excess opioid effect when starting or stopping ritonavir and titrate methadone to clinical response. Check the ECG in patients with QT risk factors.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Methadone and Ritonavir, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
Other interactions of Methadone
- Alvimopan + Methadone Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Methadone Contraindicated
- Droperidol + Methadone Contraindicated
- Ibutilide + Methadone Contraindicated
- Isocarboxazid + Methadone Contraindicated
- Lefamulin + Methadone 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 Methadone with Ritonavir?
MediHelp rates the interaction as moderate. Methadone 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 has mixed effects on methadone, and in practice usually lowers methadone concentrations, which can cause withdrawal. Methadone dose needs may rise, especially with boosted protease inhibitor regimens.
How serious is the interaction between Methadone 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: Monitor for withdrawal or excess opioid effect when starting or stopping ritonavir and titrate methadone to clinical response. Check the ECG in patients with QT risk factors.
What other medicines interact with Methadone?
MediHelp also lists interactions of Methadone with, for example, Alvimopan, Calcium / magnesium / potassium / sodium oxybates, Droperidol. The full list is on the Methadone page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
