What the FDA labels say about taking them together
Carbamazepine and ondansetron
Ondansetron's FDA label of January 8, 2026 names carbamazepine in its drug interactions section; the carbamazepine labels PlainMeds reads (3) do not name ondansetron. The ondansetron label: “In patients treated with potent inducers of CYP3A4, the clearance of ondansetron was significantly increased and ondansetron blood concentrations were decreased.”
Check it at the source: the carbamazepine FDA label on DailyMed (effective August 20, 2026, Novartis Pharmaceuticals Corporation); the ondansetron FDA label on DailyMed (effective January 8, 2026, Glenmark Pharmaceuticals Inc., USA).
What does the carbamazepine label say about ondansetron?
Carbamazepine's label (effective August 20, 2026) and its 2 other brand-application labels do not name ondansetron 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 ondansetron label say about carbamazepine?
Ondansetron label, drug interactionsIn patients treated with potent inducers of CYP3A4 (i.e., phenytoin, carbamazepine, and rifampin), the clearance of ondansetron was significantly increased and ondansetron blood concentrations were decreased.
Source: FDA drug label (Ondansetron), Glenmark Pharmaceuticals Inc., USA, effective January 8, 2026 (SPL set eee5217a-eba8-463a-812d-bf3c66f0934f), 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 | Ondansetron | |
|---|---|---|
| Labeled for | Bipolar disorder, Seizures and epilepsy | Nausea and vomiting |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $0.119 per tablet 200 mg tablet | $0.0582 per tablet 4 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