Drug interactions
Azithromycin + Ketoconazole
Severity: Major
Azithromycin and Ketoconazole: major 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 can lengthen the QT interval, and combined use may raise the risk of torsades de pointes. Ketoconazole is also a strong CYP3A4 inhibitor, which may add to the risk with other interacting drugs.
What this interaction means in plain words
Azithromycin and Ketoconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Azithromycin belongs to Anti Bacterial; Ketoconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation through blockade of cardiac potassium channels.
What to do
Avoid the combination if possible. If it is necessary, correct electrolytes and monitor ECG and QTc, especially in patients with cardiac risk factors.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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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
Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Azithromycin with Ketoconazole?
MediHelp rates the interaction as major. Azithromycin and Ketoconazole can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs can lengthen the QT interval, and combined use may raise the risk of torsades de pointes. Ketoconazole is also a strong CYP3A4 inhibitor, which may add to the risk with other interacting drugs.
How serious is the interaction between Azithromycin and Ketoconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible. If it is necessary, correct electrolytes and monitor ECG and QTc, especially in patients with cardiac risk factors.
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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