What the FDA labels say about taking them together
Sodium phenylbutyrate and valproic acid
Sodium phenylbutyrate's FDA label of July 17, 2026 names valproic acid in its drug interactions section; the valproic acid label PlainMeds reads does not name sodium phenylbutyrate. The sodium phenylbutyrate label: “DRUG INTERACTIONS Valproic Acid, Haloperidol, or Corticosteroids: May increase plasma ammonia level; monitor ammonia levels closely.”
Check it at the source: the sodium phenylbutyrate FDA label on DailyMed (effective July 17, 2026, Medunik USA); the valproic acid FDA label on DailyMed (effective January 24, 2025, PAI Holdings, LLC dba PAI Pharma).
What does the sodium phenylbutyrate label say about valproic acid?
Sodium phenylbutyrate label, drug interactionsDRUG INTERACTIONS Valproic Acid, Haloperidol, or Corticosteroids: May increase plasma ammonia level; monitor ammonia levels closely.
Source: FDA drug label (Olpruva, NDA214860), Acer Therapeutics Inc., effective December 18, 2024 (SPL set 89abc31c-43e8-4809-9eb7-172cb31a86f1), via openFDA
Source: FDA drug label (PHEBURANE), Medunik USA, effective July 17, 2026 (SPL set d15f2cbf-4d22-40b5-8ef9-16b9d323a7f9), via openFDA; the full label on DailyMed
What does the valproic acid label say about sodium phenylbutyrate?
Valproic acid's label (effective January 24, 2025) does not name sodium phenylbutyrate in these sections. A label lists what its studies and reports found; it is not a complete list.
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
| Sodium phenylbutyrate | Valproic acid | |
|---|---|---|
| Labeled for | n/a | Seizures and epilepsy, Migraine |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | n/a | $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