What the FDA labels say about taking them together
Fosamprenavir and methadone
Fosamprenavir's FDA label of September 15, 2023 names methadone in its drug interactions section; the methadone labels PlainMeds reads (4) do not name fosamprenavir. The fosamprenavir label: “Data suggest that the interaction is not clinically relevant; however, patients should be monitored for opiate withdrawal symptoms.”
Check it at the source: the fosamprenavir FDA label on DailyMed (effective September 15, 2023, Mylan Pharmaceuticals Inc.); the methadone FDA label on DailyMed (effective December 8, 2025, Epic Pharma, LLC).
What does the fosamprenavir label say about methadone?
Fosamprenavir label, drug interactionsConcomitant Drug Class/Drug Name: Narcotic analgesic: Methadone; Effect on Concentration of Amprenavir or Concomitant Drug: ↓ Methadone; Clinical Comment: Data suggest that the interaction is not clinically relevant; however, patients should be monitored for opiate withdrawal symptoms.
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 methadone label say about fosamprenavir?
Methadone's label (effective December 8, 2025) and its 3 other brand-application labels 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 (Methadone Hydrochloride), Epic Pharma, LLC, effective December 8, 2025 (SPL set 6da7501b-b881-4bc7-891a-74214a00a3ac), 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 | Methadone | |
|---|---|---|
| Labeled for | HIV | Pain, Opioid use disorder |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $0.177 per tablet 10 mg tablet |
| 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