What the FDA labels say about taking them together
Doxazosin and nelfinavir
Doxazosin's FDA label (Cardura Xl) of May 15, 2023 names nelfinavir in its drug interactions section; the nelfinavir 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 nelfinavir FDA label on DailyMed (effective December 11, 2025, AGOURON).
What does the doxazosin label say about nelfinavir?
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 nelfinavir label say about doxazosin?
Nelfinavir's label (effective December 11, 2025) 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 (VIRACEPT), AGOURON, effective December 11, 2025 (SPL set e72c2bc6-9462-4a2e-8e1d-b97592376cbd), 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 | Nelfinavir | |
|---|---|---|
| Labeled for | Enlarged prostate (BPH), High blood pressure | HIV |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0752 per tablet 1 mg tablet | n/a |
| Shortage now | No current entry | No current entry |
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