What the FDA labels say about taking them together
Fosamprenavir and lansoprazole
Fosamprenavir's FDA label of September 15, 2023 names lansoprazole in its drug interactions section; the lansoprazole labels PlainMeds reads (2) do not name fosamprenavir. The fosamprenavir label: “Proton pump inhibitors can be administered at the same time as a dose of fosamprenavir with no change in plasma amprenavir concentrations.”
Check it at the source: the fosamprenavir FDA label on DailyMed (effective September 15, 2023, Mylan Pharmaceuticals Inc.); the lansoprazole FDA label on DailyMed (effective June 24, 2025, L. Perrigo Company).
What does the fosamprenavir label say about lansoprazole?
Fosamprenavir label, drug interactionsConcomitant Drug Class/Drug Name: Proton pump inhibitors: Esomeprazole, lansoprazole, omeprazole, pantoprazole, rabeprazole; Effect on Concentration of Amprenavir or Concomitant Drug: Fosamprenavir: ↔ Amprenavir ↑ Esomeprazole Fosamprenavir/ ritonavir: ↔ Amprenavir ↔ Esomeprazole; Clinical Comment: Proton pump inhibitors can be administered at the same time as a dose of fosamprenavir with no change in plasma amprenavir concentrations.
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
What does the lansoprazole label say about fosamprenavir?
Lansoprazole's label (effective June 24, 2025) and its 1 other brand-application label do not name fosamprenavir in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Prevacid 24 HR), L. Perrigo Company, effective June 24, 2025 (SPL set 205c9c1e-b422-4e86-a4b0-714b608adc19), 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
| Fosamprenavir | Lansoprazole | |
|---|---|---|
| Labeled for | HIV | Acid reflux and ulcers |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.106 per capsule 30 mg capsule |
| 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