What the FDA labels say about taking them together
Glycerol phenylbutyrate and sodium phenylbutyrate
Glycerol phenylbutyrate's FDA label of October 29, 2025 names sodium phenylbutyrate in its warnings and precautions section; the sodium phenylbutyrate labels PlainMeds reads (3) do not name glycerol phenylbutyrate.
Check it at the source: the glycerol phenylbutyrate FDA label on DailyMed (effective October 29, 2025, Horizon Therapeutics USA, Inc.); the sodium phenylbutyrate FDA label on DailyMed (effective July 17, 2026, Medunik USA).
What does the glycerol phenylbutyrate label say about sodium phenylbutyrate?
Glycerol phenylbutyrate label, warnings and precautionsIn clinical trials in patients with UCDs who had been on sodium phenylbutyrate prior to administration of RAVICTI, adverse reactions of headache, fatigue, symptoms of peripheral neuropathy, seizures, tremor and/or dizziness were reported.
Source: FDA drug label (Ravicti), Horizon Therapeutics USA, Inc., effective October 29, 2025 (SPL set 900e7dc0-9afe-4f50-80de-90567bb78519), via openFDA; the full label on DailyMed
What does the sodium phenylbutyrate label say about glycerol phenylbutyrate?
Sodium phenylbutyrate's label (effective July 17, 2026) and its 2 other brand-application labels do not name glycerol phenylbutyrate in these sections. A label lists what its studies and reports found; it is not a complete list.
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
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
| Glycerol phenylbutyrate | Sodium phenylbutyrate | |
|---|---|---|
| Labeled for | n/a | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | n/a |
| 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