What the FDA labels say about taking them together
Calcifediol and nelfinavir
Calcifediol's FDA label of January 19, 2024 names nelfinavir in its drug interactions section; the nelfinavir label PlainMeds reads does not name calcifediol. The calcifediol label: “CYP3A Inhibitors Cytochrome P450 inhibitors, such as ketoconazole, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin or voriconazole, may inhibit enzymes …”
Check it at the source: the calcifediol FDA label on DailyMed (effective January 19, 2024, OPKO Pharmaceuticals LLC); the nelfinavir FDA label on DailyMed (effective December 11, 2025, AGOURON).
What does the calcifediol label say about nelfinavir?
Calcifediol label, drug interactionsCYP3A Inhibitors Cytochrome P450 inhibitors, such as ketoconazole, atazanavir, clarithromycin, indinavir, itraconazole, nefazodone, nelfinavir, ritonavir, saquinavir, telithromycin or voriconazole, may inhibit enzymes involved in vitamin D metabolism (CYP24A1 and CYP27B1), and may alter serum levels of calcifediol.
Source: FDA drug label (Rayaldee), NDA208010 (Eirgen), as published by OPKO Pharmaceuticals LLC, effective January 19, 2024 (SPL set 6a95effd-32a5-46b6-a30e-7f4f9bf8cc77), via openFDA; the full label on DailyMed
What does the nelfinavir label say about calcifediol?
Nelfinavir's label (effective December 11, 2025) does not name calcifediol 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
| Calcifediol | Nelfinavir | |
|---|---|---|
| Labeled for | n/a | HIV |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $41.26 per capsule 30 mcg capsule (hard) | 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