What the FDA labels say about taking them together
Doxazosin and ritonavir
Doxazosin's FDA label (Cardura Xl) of May 15, 2023 names ritonavir in its drug interactions section; the ritonavir label PlainMeds reads does not name doxazosin.
Check it at the source: the doxazosin FDA label on DailyMed (effective October 15, 2023, Viatris Specialty LLC); the ritonavir FDA label on DailyMed (effective July 23, 2026, AbbVie Inc.).
What does the doxazosin label say about ritonavir?
Cardura Xl label (Viatris Specialty LLC, May 15, 2023), drug interactionsCaution should be exercised when concomitantly administering CARDURA XL with a strong CYP 3A4 inhibitor, such as atazanavir, clarithromycin, indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, or voriconazole [see Clinical Pharmacology (12.3) ].
Cardura Xl label (Viatris Specialty LLC, May 15, 2023), warnings and precautionsCYP 3A4 Inhibitors Caution should be exercised when concomitantly administering CARDURA XL with a strong CYP 3A4 inhibitor, such as atazanavir, clarithromycin, indinavir, itraconazole, ketoconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin, or voriconazole.
Source: FDA drug label (Cardura Xl, NDA021269), Viatris Specialty LLC, effective May 15, 2023 (SPL set 355bcdce-0481-48ba-8ebd-2009106aaf77), via openFDA
Source: FDA drug label (Cardura), Viatris Specialty LLC, effective October 15, 2023 (SPL set 5e1f5e49-2da1-43ab-9795-228a8bcc5a82), via openFDA; the full label on DailyMed
What does the ritonavir label say about doxazosin?
Ritonavir's label (effective July 23, 2026) does not name doxazosin in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Norvir), AbbVie Inc., effective July 23, 2026 (SPL set 2849298e-de6e-47bb-8194-56e075b33fc3), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Doxazosin | Ritonavir | |
|---|---|---|
| Labeled for | Enlarged prostate (BPH), High blood pressure | HIV |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.0752 per tablet 1 mg tablet | $0.607 per tablet 100 mg tablet |
| Shortage now | No current entry | A presentation being discontinued |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once