What the FDA labels say about taking them together
Rifampin and valproic acid
Valproic acid's FDA label of January 24, 2025 names rifampin in its drug interactions section; the rifampin label PlainMeds reads does not name valproic acid. The valproic acid label: “DRUG INTERACTIONS Hepatic enzyme-inducing drugs can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance.”
Check it at the source: the rifampin FDA label on DailyMed (effective February 11, 2026, Lupin Pharmaceuticals, Inc.); the valproic acid FDA label on DailyMed (effective January 24, 2025, PAI Holdings, LLC dba PAI Pharma).
What does the rifampin label say about valproic acid?
Rifampin's label (effective February 11, 2026) does not name valproic acid 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
What does the valproic acid label say about rifampin?
Valproic acid label, drug interactionsDRUG INTERACTIONS Hepatic enzyme-inducing drugs (e.g., phenytoin, carbamazepine, phenobarbital, primidone, rifampin) can increase valproate clearance, while enzyme inhibitors (e.g., felbamate) can decrease valproate clearance.
Source: FDA drug label (VALPROIC ACID), PAI Holdings, LLC dba PAI Pharma, effective January 24, 2025 (SPL set 7d5cb52e-37dd-4dfa-a6f4-09f9548846c6), 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
| Rifampin | Valproic acid | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy, Migraine |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.679 per capsule 300 mg capsule | $0.243 per capsule 250 mg capsule |
| Shortage now | In shortage | Listed; available |
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