What the FDA labels say about taking them together
Ondansetron and rifampin
Ondansetron's FDA label of January 8, 2026 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does 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 ondansetron FDA label on DailyMed (effective January 8, 2026, Glenmark Pharmaceuticals Inc., USA); the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.).
What does the ondansetron label say about rifampin?
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
What does the rifampin label say about ondansetron?
Rifampin's label (effective February 11, 2026) does 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 (rifampin), Lupin Pharmaceuticals, Inc., effective February 11, 2026 (SPL set b56004f0-f23d-47f6-80c7-39884fccbccc), 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
| Ondansetron | Rifampin | |
|---|---|---|
| Labeled for | Nausea and vomiting | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0582 per tablet 4 mg tablet | $0.679 per capsule 300 mg capsule |
| Shortage now | No current entry | In shortage |
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