Drug interactions
Itraconazole + Nirmatrelvir / ritonavir
Severity: Moderate
Itraconazole and Nirmatrelvir / ritonavir: 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
Ritonavir-boosted nirmatrelvir strongly inhibits CYP3A4 and raises itraconazole concentrations. This increases the risk of itraconazole toxicity such as edema, heart failure exacerbation and hepatotoxicity, and itraconazole may modestly increase ritonavir exposure.
What this interaction means in plain words
Itraconazole and Nirmatrelvir / ritonavir 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
Inhibition of CYP3A4 metabolism of itraconazole by ritonavir and nirmatrelvir, with reciprocal CYP3A4 inhibition.
What to do
Limit itraconazole to no more than 200 mg/day while receiving the 5-day course. Monitor for itraconazole adverse effects.
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 Nirmatrelvir / ritonavir?
MediHelp rates the interaction as moderate. Itraconazole and Nirmatrelvir / ritonavir 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. Ritonavir-boosted nirmatrelvir strongly inhibits CYP3A4 and raises itraconazole concentrations. This increases the risk of itraconazole toxicity such as edema, heart failure exacerbation and hepatotoxicity, and itraconazole may modestly increase ritonavir exposure.
How serious is the interaction between Itraconazole and Nirmatrelvir / ritonavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Limit itraconazole to no more than 200 mg/day while receiving the 5-day course. Monitor for itraconazole adverse effects.
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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