What the FDA labels say about taking them together
Carbamazepine and fostemsavir
Fostemsavir's FDA label of February 13, 2024 names carbamazepine in its contraindications section; the carbamazepine labels PlainMeds reads (3) do not name fostemsavir. The fostemsavir label: “Coadministration is contraindicated due to potential for loss of therapeutic effect to RUKOBIA.”
Check it at the source: the carbamazepine FDA label on DailyMed (effective August 20, 2026, Novartis Pharmaceuticals Corporation); the fostemsavir FDA label on DailyMed (effective February 13, 2024, ViiV Healthcare Company).
What does the carbamazepine label say about fostemsavir?
Carbamazepine's label (effective August 20, 2026) and its 2 other brand-application labels do not name fostemsavir 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 fostemsavir label say about carbamazepine?
Fostemsavir label, contraindicationsEnzalutamide o Anticonvulsants: Carbamazepine, phenytoin o Antimycobacterial: Rifampin o Antineoplastic:
Fostemsavir label, drug interactionsConcomitant Drug Class/Drug Name: Anticonvulsants: Carbamazepine Phenytoin; Effect on Concentration of Temsavir and/or Concomitant Drug: ↓Temsavir; Clinical Comment: Coadministration is contraindicated due to potential for loss of therapeutic effect to RUKOBIA [see Contraindications ()].
Source: FDA drug label (Rukobia), ViiV Healthcare Company, effective February 13, 2024 (SPL set a21006b7-6d6f-4f06-81b4-17978756452b), 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 | Fostemsavir | |
|---|---|---|
| Labeled for | Bipolar disorder, Seizures and epilepsy | HIV |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.119 per tablet 200 mg tablet | $156.84 per tablet 600 mg tablet |
| 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