Drug interactions
Diazepam + Methadone
Severity: Major
Diazepam and Methadone: 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
Combining an opioid with a benzodiazepine increases the risk of profound sedation, respiratory depression, coma and death. This is the subject of regulatory boxed warnings, and methadone's long half-life prolongs the risk.
What this interaction means in plain words
Diazepam and Methadone 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.
Diazepam belongs to Musculoskeletal; Methadone belongs to Musculoskeletal.
Why it happens
Additive CNS and respiratory depression via opioid and GABA-A receptor effects.
What to do
Avoid the combination where possible; if necessary use the lowest doses for the shortest duration and monitor for sedation and respiratory depression. Counsel patients and caregivers about warning signs and avoiding alcohol.
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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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 Diazepam
Frequently asked questions
Can I take Diazepam with Methadone?
MediHelp rates the interaction as major. Diazepam and Methadone 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. Combining an opioid with a benzodiazepine increases the risk of profound sedation, respiratory depression, coma and death. This is the subject of regulatory boxed warnings, and methadone's long half-life prolongs the risk.
How serious is the interaction between Diazepam and Methadone?
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 where possible; if necessary use the lowest doses for the shortest duration and monitor for sedation and respiratory depression. Counsel patients and caregivers about warning signs and avoiding alcohol.
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.
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