Drug interactions
Methadone + Sulfamethoxazole
Severity: Moderate
Methadone and Sulfamethoxazole: 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
Both drugs have been associated with QT prolongation, although the effect of sulfamethoxazole is modest and reported mainly with trimethoprim combinations. The combination may add to arrhythmia risk in patients with other risk factors.
What this interaction means in plain words
Methadone and Sulfamethoxazole 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.
Why it happens
Possible additive QT interval prolongation.
What to do
Check electrolytes and consider an ECG in patients with additional QT risk factors. Choose an alternative antibiotic if QTc is already prolonged.
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
Frequently asked questions
Can I take Methadone with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Methadone and Sulfamethoxazole 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. Both drugs have been associated with QT prolongation, although the effect of sulfamethoxazole is modest and reported mainly with trimethoprim combinations. The combination may add to arrhythmia risk in patients with other risk factors.
How serious is the interaction between Methadone and Sulfamethoxazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check electrolytes and consider an ECG in patients with additional QT risk factors. Choose an alternative antibiotic if QTc is already prolonged.
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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