Drug interactions
Clarithromycin + Itraconazole
Severity: Major
Clarithromycin and Itraconazole: major interaction.
Last updated Sources: US FDA label
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 inhibits CYP3A4 and can increase clarithromycin concentrations, while clarithromycin can in turn raise itraconazole levels. Both drugs can prolong the QT interval, so combined use increases arrhythmia risk.
What this interaction means in plain words
Clarithromycin and Itraconazole 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.
Clarithromycin belongs to Anti Bacterial; Itraconazole belongs to Anti Fungals.
Why it happens
Mutual CYP3A4 inhibition combined with additive QT prolongation.
What to do
Avoid combining the two if alternatives exist. If necessary, monitor the ECG, electrolytes, and signs of toxicity from either drug.
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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References
Other interactions of Clarithromycin
- Astemizole + Clarithromycin Contraindicated
- Avanafil + Clarithromycin Contraindicated
- Cisapride + Clarithromycin Contraindicated
- Clarithromycin + Colchicine Contraindicated
- Clarithromycin + Conivaptan Contraindicated
- Clarithromycin + Dihydroergotamine Contraindicated
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 Clarithromycin with Itraconazole?
MediHelp rates the interaction as major. Clarithromycin and Itraconazole 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. Itraconazole inhibits CYP3A4 and can increase clarithromycin concentrations, while clarithromycin can in turn raise itraconazole levels. Both drugs can prolong the QT interval, so combined use increases arrhythmia risk.
How serious is the interaction between Clarithromycin and Itraconazole?
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 combining the two if alternatives exist. If necessary, monitor the ECG, electrolytes, and signs of toxicity from either drug.
What other medicines interact with Clarithromycin?
MediHelp also lists interactions of Clarithromycin with, for example, Astemizole, Avanafil, Cisapride. The full list is on the Clarithromycin page.
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