What the label lists and what reports show
Sodium phenylbutyrate side effects
Sodium phenylbutyrate's FDA label: “Most common adverse reactions (incidence ≥ 3%) are amenorrhea or menstrual dysfunction (irregular menstrual cycles), decreased appetite, body odor and bad taste or taste aversion.” FAERS holds 420 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is hyperammonaemia (56 reports).
- Generic listed
Check it at the source: the sodium phenylbutyrate FDA label on DailyMed (effective July 17, 2026, Medunik USA); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of PHEBURANE?PHEBURANE can cause serious side effects, including: Nervous system problems (neurotoxicity). Call your healthcare provider right away if you get any of the following symptoms during treatment with PHEBURANE: sleepiness tiredness lightheadedness vomiting nausea headache confusion Low potassium levels in your blood (hypokalemia). Your healthcare provider will monitor your blood potassium levels during treatment with PHEBURANE and treat if needed. Conditions related to swelling (edema). PHEBURANE contains salt (sodium), which can cause swelling from salt and water retention. Your healthcare provider will decide if PHEBURANE is right for you if you have certain medical conditions that can cause swelling, such as heart failure, liver problems or kidney problems. […]
Source: FDA drug label, Medunik USA, effective July 17, 2026 (SPL set d15f2cbf-4d22-40b5-8ef9-16b9d323a7f9), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (incidence ≥ 3%) are amenorrhea or menstrual dysfunction (irregular menstrual cycles), decreased appetite, body odor and bad taste or taste aversion.
From the label: adverse reactions, continuedThe following adverse reactions associated with the use of sodium phenylbutyrate were identified in clinical studies or postmarketing reports. Because some of these reactions were reported voluntarily and from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Most common adverse reactions (incidence ≥ 3%) are amenorrhea or menstrual dysfunction (irregular menstrual cycles), decreased appetite, body odor and bad taste or taste aversion.
Source: FDA drug label, Medunik USA, effective July 17, 2026 (SPL set d15f2cbf-4d22-40b5-8ef9-16b9d323a7f9), via openFDA; the full label on DailyMed
What do FAERS reports show?
420 reports list sodium phenylbutyrate among the medicines taken, each a report of something that happened, not proof the medicine caused it; 84 are coded as a death and 164 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 7 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Sodium phenylbutyrate: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions