What the FDA labels say about taking them together
Primidone and valproic acid
Valproic acid's FDA label of January 24, 2025 names primidone in its drug interactions section; primidone's label does not name valproic acid itself but warns about its class (Anti-seizure medicines). 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 primidone FDA label on DailyMed (effective September 10, 2026, Bausch Health US, LLC); the valproic acid FDA label on DailyMed (effective January 24, 2025, PAI Holdings, LLC dba PAI Pharma).
What does the primidone label say about valproic acid?
Primidone's label does not name valproic acid itself; it warns about its class (Anti-seizure medicines):
Primidone label, warningsSuicidal Behavior and Ideation Antiepileptic drugs (AEDs), including MYSOLINE, increase the risk of suicidal thoughts or behavior in patients taking these drugs for any indication.
Primidone label, warningsPatients treated with any AED for any indication should be monitored for the emergence or worsening of depression, suicidal thoughts or behavior, and/or any unusual changes in mood or behavior.
Source: FDA drug label (Mysoline), NDA009170 (Valeant), as published by Bausch Health US, LLC, effective September 10, 2026 (SPL set af593171-dabb-4ea3-b44c-89ed457b2c46), via openFDA; the full label on DailyMed
What does the valproic acid label say about primidone?
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
| Primidone | Valproic acid | |
|---|---|---|
| Labeled for | Seizures and epilepsy | Seizures and epilepsy, Migraine |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.0914 per tablet 50 mg tablet | $0.243 per capsule 250 mg capsule |
| Shortage now | No current entry | 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