Drug interactions
Dutasteride-tamsulosin + Nirmatrelvir / ritonavir
Severity: Major
Dutasteride-tamsulosin and Nirmatrelvir / ritonavir: 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 can markedly raise tamsulosin exposure. The risk is symptomatic hypotension and syncope, and inhibition persists for days after the course ends.
What this interaction means in plain words
Dutasteride-tamsulosin and Nirmatrelvir / ritonavir 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 inhibits CYP3A4 (and CYP2D6), reducing tamsulosin clearance.
What to do
Hold tamsulosin during the 5-day course and for about 3 days after finishing, then resume. Counsel the patient about dizziness and fall risk.
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 Dutasteride-tamsulosin
Frequently asked questions
Can I take Dutasteride-tamsulosin with Nirmatrelvir / ritonavir?
MediHelp rates the interaction as major. Dutasteride-tamsulosin and Nirmatrelvir / ritonavir 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 can markedly raise tamsulosin exposure. The risk is symptomatic hypotension and syncope, and inhibition persists for days after the course ends.
How serious is the interaction between Dutasteride-tamsulosin and Nirmatrelvir / ritonavir?
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 the 5-day course and for about 3 days after finishing, then resume. Counsel the patient about dizziness and fall risk.
What other medicines interact with Dutasteride-tamsulosin?
MediHelp also lists interactions of Dutasteride-tamsulosin with, for example, Alfuzosin, Amifostine, Atazanavir. The full list is on the Dutasteride-tamsulosin page.
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