Drug interactions
Methadone + Voriconazole
Severity: Major
Methadone and Voriconazole: major interaction.
Last updated Sources: US FDA label
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
Voriconazole inhibits CYP2C19, CYP3A4 and CYP2C9, which raises methadone exposure, particularly of the active R-enantiomer. Both drugs also prolong the QT interval, so toxicity can include sedation, respiratory depression and torsades de pointes.
What this interaction means in plain words
Methadone and Voriconazole 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.
Methadone belongs to Musculoskeletal; Voriconazole belongs to Anti Fungals.
Why it happens
Inhibition of CYP2C19 and CYP3A4 metabolism of methadone by voriconazole, plus additive QT prolongation.
What to do
Monitor closely for opioid toxicity and QT prolongation with ECG and electrolytes, and reduce the methadone dose when needed. Reassess the dose when voriconazole is stopped because levels will fall.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Methadone and Voriconazole, 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.
References
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 Voriconazole
- Avanafil + Voriconazole Contraindicated
- Butabarbital + Voriconazole Contraindicated
- Carbamazepine + Voriconazole Contraindicated
- Conivaptan + Voriconazole Contraindicated
- Dihydroergotamine intranasal + Voriconazole Contraindicated
- Dihydroergotamine + Voriconazole Contraindicated
Frequently asked questions
Can I take Methadone with Voriconazole?
MediHelp rates the interaction as major. Methadone and Voriconazole 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. Voriconazole inhibits CYP2C19, CYP3A4 and CYP2C9, which raises methadone exposure, particularly of the active R-enantiomer. Both drugs also prolong the QT interval, so toxicity can include sedation, respiratory depression and torsades de pointes.
How serious is the interaction between Methadone and Voriconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor closely for opioid toxicity and QT prolongation with ECG and electrolytes, and reduce the methadone dose when needed. Reassess the dose when voriconazole is stopped because levels will fall.
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.
