Drug interactions
Sulfamethoxazole + Voriconazole
Severity: Moderate
Sulfamethoxazole and Voriconazole: 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 agents have been associated with QT prolongation, although sulfamethoxazole's effect is weak and evidence is limited. The combined risk of arrhythmia is likely small except in patients with other risk factors.
What this interaction means in plain words
Sulfamethoxazole and Voriconazole 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 prolongation; the mechanism for sulfamethoxazole is not well established.
What to do
Check baseline ECG and correct hypokalemia or hypomagnesemia in patients with other QT risk factors. Monitor ECG if other QT-prolonging drugs are present.
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 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 Sulfamethoxazole with Voriconazole?
MediHelp rates the interaction as moderate. Sulfamethoxazole and Voriconazole 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 agents have been associated with QT prolongation, although sulfamethoxazole's effect is weak and evidence is limited. The combined risk of arrhythmia is likely small except in patients with other risk factors.
How serious is the interaction between Sulfamethoxazole and Voriconazole?
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 baseline ECG and correct hypokalemia or hypomagnesemia in patients with other QT risk factors. Monitor ECG if other QT-prolonging drugs are present.
What other medicines interact with Voriconazole?
MediHelp also lists interactions of Voriconazole with, for example, Avanafil, Butabarbital, Carbamazepine. The full list is on the Voriconazole page.
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