What the FDA labels say about taking them together
Carbamazepine and fosamprenavir
Fosamprenavir's FDA label of September 15, 2023 names carbamazepine in its drug interactions section; the carbamazepine labels PlainMeds reads (3) do not name fosamprenavir. The fosamprenavir label: “Use with caution. Fosamprenavir may be less effective due to decreased amprenavir plasma concentrations in patients taking these agents concomitantly.”
Check it at the source: the carbamazepine FDA label on DailyMed (effective August 20, 2026, Novartis Pharmaceuticals Corporation); the fosamprenavir FDA label on DailyMed (effective September 15, 2023, Mylan Pharmaceuticals Inc.).
What does the carbamazepine label say about fosamprenavir?
Carbamazepine's label (effective August 20, 2026) and its 2 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 (Tegretol), Novartis Pharmaceuticals Corporation, effective August 20, 2026 (SPL set 8d409411-aa9f-4f3a-a52c-fbcb0c3ec053), via openFDA; the full label on DailyMed
What does the fosamprenavir label say about carbamazepine?
Fosamprenavir label, drug interactionsConcomitant Drug Class/Drug Name: Anticonvulsants: Carbamazepine, phenobarbital, phenytoin; Effect on Concentration of Amprenavir or Concomitant Drug: Fosamprenavir: ↓ Amprenavir; Clinical Comment: Use with caution. Fosamprenavir may be less effective due to decreased amprenavir plasma concentrations in patients taking these agents concomitantly.
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
| Carbamazepine | Fosamprenavir | |
|---|---|---|
| Labeled for | Bipolar disorder, Seizures and epilepsy | HIV |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.119 per tablet 200 mg tablet | 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