What the FDA labels say about taking them together
Cimetidine and fosamprenavir
Fosamprenavir's FDA label of September 15, 2023 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does not name fosamprenavir. The fosamprenavir label: “Use with caution. Fosamprenavir may be less effective due to decreased amprenavir plasma concentrations.”
Check it at the source: the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.); the fosamprenavir FDA label on DailyMed (effective September 15, 2023, Mylan Pharmaceuticals Inc.).
What does the cimetidine label say about fosamprenavir?
Cimetidine's label (effective July 15, 2026) does 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 (Cimetidine), Mylan Pharmaceuticals Inc., effective July 15, 2026 (SPL set 06c0a509-026f-44e0-9975-a94a8de51d43), via openFDA; the full label on DailyMed
What does the fosamprenavir label say about cimetidine?
Fosamprenavir label, drug interactionsConcomitant Drug Class/Drug Name: Histamine H 2 -receptor antagonists: Cimetidine, famotidine, nizatidine, ranitidine; Effect on Concentration of Amprenavir or Concomitant Drug: Fosamprenavir: ↓ Amprenavir Fosamprenavir/ ritonavir: Interaction not evaluated; Clinical Comment: Use with caution. Fosamprenavir may be less effective due to decreased amprenavir plasma 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
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
| Cimetidine | Fosamprenavir | |
|---|---|---|
| Labeled for | Acid reflux and ulcers | HIV |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.236 per tablet 300 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