Drug interactions
Azithromycin + Sulfamethoxazole
Severity: Minor
Azithromycin and Sulfamethoxazole: minor 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, so combining them may add to arrhythmia risk. The effect of sulfamethoxazole is weak and the risk is mainly relevant in patients with other predisposing factors.
What this interaction means in plain words
Azithromycin and Sulfamethoxazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Possible additive QT prolongation.
What to do
No routine action is needed in low-risk patients. In patients with QT risk factors, check electrolytes and consider an ECG.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Azithromycin
- Azithromycin + Cisapride Contraindicated
- Azithromycin + Domperidone Contraindicated
- Azithromycin + Dronedarone Contraindicated
- Azithromycin + Pimozide Contraindicated
- Azithromycin + Piperaquine Contraindicated
- Azithromycin + Thioridazine Contraindicated
Frequently asked questions
Can I take Azithromycin with Sulfamethoxazole?
MediHelp rates the interaction as minor. Azithromycin and Sulfamethoxazole have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Both agents have been associated with QT prolongation, so combining them may add to arrhythmia risk. The effect of sulfamethoxazole is weak and the risk is mainly relevant in patients with other predisposing factors.
How serious is the interaction between Azithromycin and Sulfamethoxazole?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine action is needed in low-risk patients. In patients with QT risk factors, check electrolytes and consider an ECG.
What other medicines interact with Azithromycin?
MediHelp also lists interactions of Azithromycin with, for example, Cisapride, Domperidone, Dronedarone. The full list is on the Azithromycin page.
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