Drug interactions
Itraconazole + Sulfamethoxazole
Severity: Moderate
Itraconazole 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
Itraconazole can prolong the QT interval, while sulfamethoxazole-trimethoprim has been associated with rare QT prolongation and arrhythmias. The additive effect is uncertain, and clinical significance is mainly in patients with other risk factors.
What this interaction means in plain words
Itraconazole 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 prolongation; the mechanism for sulfamethoxazole is not well established.
What to do
Check ECG and correct hypokalemia and hypomagnesemia in patients with other QT risk factors. Choose an alternative if the baseline QTc is markedly 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 Itraconazole
- Alfuzosin + Itraconazole Contraindicated
- Alprazolam + Itraconazole Contraindicated
- Avanafil + Itraconazole Contraindicated
- Conivaptan + Itraconazole Contraindicated
- Dihydroergotamine intranasal + Itraconazole Contraindicated
- Dihydroergotamine + Itraconazole Contraindicated
Frequently asked questions
Can I take Itraconazole with Sulfamethoxazole?
MediHelp rates the interaction as moderate. Itraconazole 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. Itraconazole can prolong the QT interval, while sulfamethoxazole-trimethoprim has been associated with rare QT prolongation and arrhythmias. The additive effect is uncertain, and clinical significance is mainly in patients with other risk factors.
How serious is the interaction between Itraconazole 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 ECG and correct hypokalemia and hypomagnesemia in patients with other QT risk factors. Choose an alternative if the baseline QTc is markedly prolonged.
What other medicines interact with Itraconazole?
MediHelp also lists interactions of Itraconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Itraconazole page.
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