Drug interactions
Nirmatrelvir / ritonavir + Tamsulosin
Severity: Major
Nirmatrelvir / ritonavir and Tamsulosin: 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
Ritonavir in this combination strongly inhibits CYP3A4 and raises tamsulosin exposure. This increases the risk of significant hypotension and syncope, and the inhibition persists for days after the course.
What this interaction means in plain words
Nirmatrelvir / ritonavir and Tamsulosin 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.
Why it happens
Ritonavir potently inhibits CYP3A4 (and to a lesser extent CYP2D6), reducing tamsulosin clearance.
What to do
Hold tamsulosin during treatment and for about 3 days after the last dose, restarting afterwards. Counsel the patient about falls and dizziness.
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 Tamsulosin
- Alfuzosin + Tamsulosin Major
- Avanafil + Tamsulosin Major
- Ceritinib + Tamsulosin Major
- Clarithromycin + Tamsulosin Major
- Cobicistat + Tamsulosin Major
- Doxazosin + Tamsulosin Major
Frequently asked questions
Can I take Nirmatrelvir / ritonavir with Tamsulosin?
MediHelp rates the interaction as major. Nirmatrelvir / ritonavir and Tamsulosin 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. Ritonavir in this combination strongly inhibits CYP3A4 and raises tamsulosin exposure. This increases the risk of significant hypotension and syncope, and the inhibition persists for days after the course.
How serious is the interaction between Nirmatrelvir / ritonavir and Tamsulosin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Hold tamsulosin during treatment and for about 3 days after the last dose, restarting afterwards. Counsel the patient about falls and dizziness.
What other medicines interact with Tamsulosin?
MediHelp also lists interactions of Tamsulosin with, for example, Alfuzosin, Avanafil, Ceritinib. The full list is on the Tamsulosin page.
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