Drug interactions
Isoniazid + Methadone
Severity: Moderate
Isoniazid and Methadone: 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 inhibits some CYP enzymes and may raise methadone concentrations, with a risk of excessive sedation, respiratory depression and QT prolongation. The data are limited and the effect is variable.
What this interaction means in plain words
Isoniazid and Methadone 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 belongs to Anti Bacterial; Methadone belongs to Musculoskeletal.
Why it happens
Isoniazid inhibits CYP3A4 and other CYP enzymes, reducing methadone clearance.
What to do
Monitor for sedation, slowed breathing and QTc changes when isoniazid is started. Reduce the methadone dose if signs of excess opioid effect appear.
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 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 Isoniazid
Frequently asked questions
Can I take Isoniazid with Methadone?
MediHelp rates the interaction as moderate. Isoniazid and Methadone 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 inhibits some CYP enzymes and may raise methadone concentrations, with a risk of excessive sedation, respiratory depression and QT prolongation. The data are limited and the effect is variable.
How serious is the interaction between Isoniazid and Methadone?
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 sedation, slowed breathing and QTc changes when isoniazid is started. Reduce the methadone dose if signs of excess opioid effect appear.
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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