Nirmatrelvir and Alfuzosin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Alfuzosin
Nirmatrelvir
No brand names on record
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased alfuzosin exposure; hypotension
Interaction Deep Dive
Although the interaction between alfuzosin, a CYP3A4 substrate, and ritonavir, a potent CYP3A4 inhibitor, has not been studied, the interaction between alfuzosin and ketoconazole, another potent CYP3A4 inhibitor, resulted in 2- to 3-fold increases in alfuzosin Cmax and AUC values1. Concomitant use of alfuzosin and nirmatrelvir/ritonavir is contraindicated due to potential for increased alfuzosin exposure and hypotension 2. Withhold alfuzosin during nirmatrelvir/ritonavir treatment and for 2 to 3 days (or longer in certain cases such as advanced patient age) after discontinuation if possible. Consider treatment with an alternative concomitant drug or COVID-19 treatment if temporarily withholding aliskiren is not clinically reasonable 3.
Why it happens (mechanism)
Inhibition of CYP3A4-mediated metabolism of alfuzosin by nirmatrelvir/ritonavir
Literature reports
1 report — tap to read
a) Although the interaction between alfuzosin, a CYP3A4 substrate, and ritonavir, a potent CYP3A4 inhibitor, has not been studied, there have been two studies in which repeated doses of ketoconazole, another potent CYP3A4 inhibitor, and alfuzosin resulted in increased alfuzosin Cmax and AUC values. In one study, alfuzosin Cmax and AUC were increased by 2.3- and 3.2-fold, respectively, when patients received repeated ketoconazole doses of 400 mg/day followed by a single 10-mg alfuzosin dose. In another study, alfuzosin Cmax and AUC were increased by 2.1- and 2.5-fold when patients received repeated ketoconazole doses of 200 mg/day followed by a single 10-mg alfuzosin dose 1.
Common questions
Can I take Nirmatrelvir and Alfuzosin together?
Increased alfuzosin exposure; hypotension Always confirm with your pharmacist or prescriber before making any change.
How serious is the Nirmatrelvir and Alfuzosin interaction?
It is rated contraindicated. These should generally not be used together.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Nirmatrelvir or Alfuzosin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (3)
- Product Information: UROXATRAL(R) extended release oral tablets, alfuzosin hcl extended release oral tablets. Sanofi-Aventis, Bridgewater, NJ, 2010.
- Pfizer Inc: Fact sheet for healthcare providers: Emergency Use Authorization for PAXLOVID(TM). US Food & Drug Administration (FDA). Silver Spring, MD. 2021.
- COVID-19 Treatment Guidelines Panel: Coronavirus disease 2019 (COVID-19) treatment guidelines. National Institutes of Health (NIH). Bethesda, MD. 2023.
Keep reading about Alfuzosin
Keep reading about Nirmatrelvir
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
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