What the FDA labels say about taking them together
Cobicistat and fosamprenavir
Cobicistat's FDA label of February 10, 2026 names fosamprenavir in its drug interactions section; the fosamprenavir label PlainMeds reads does not name cobicistat. The cobicistat label: “Coadministration of TYBOST with fosamprenavir, saquinavir, or tipranavir is not recommended because pharmacokinetic data are not available to provide appropriate dosing recommendations.”
Check it at the source: the cobicistat FDA label on DailyMed (effective February 10, 2026, Gilead Sciences, Inc.); the fosamprenavir FDA label on DailyMed (effective September 15, 2023, Mylan Pharmaceuticals Inc.).
What does the cobicistat label say about fosamprenavir?
Cobicistat label, drug interactionsCoadministration of TYBOST with fosamprenavir, saquinavir, or tipranavir is not recommended because pharmacokinetic data are not available to provide appropriate dosing recommendations.
Cobicistat label, warnings and precautionsMore than one antiretroviral that requires pharmacokinetic enhancement (i.e., two protease inhibitors or a protease inhibitor in combination with elvitegravir) Darunavir in combination with efavirenz, nevirapine, or etravirine Atazanavir in combination with etravirine Atazanavir in combination with efavirenz in treatment-experienced patients Darunavir 600 mg twice daily Other HIV-1 protease inhibitors including fosamprenavir, saquinavir, or tipranavir TYBOST in combination with fixed-dose combination tablets that contain cobicistat is not recommended.
Source: FDA drug label (Tybost), Gilead Sciences, Inc., effective February 10, 2026 (SPL set 3784c35c-e87f-410c-900b-8fd6313c6010), via openFDA; the full label on DailyMed
What does the fosamprenavir label say about cobicistat?
Fosamprenavir's label (effective September 15, 2023) does not name cobicistat in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Fosamprenavir Calcium), Mylan Pharmaceuticals Inc., effective September 15, 2023 (SPL set 3a1424d8-844c-4e24-9ebd-b2c2b61b61a3), 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
| Cobicistat | Fosamprenavir | |
|---|---|---|
| Labeled for | HIV | HIV |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | n/a |
| Shortage now | A presentation being discontinued | 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