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Glycerol phenylbutyrate Side Effects

Medically reviewed by Last updated on Aug 30, 2022.


Commonly reported side effects of glycerol phenylbutyrate include: dizziness, fatigue, headache, nausea, and vomiting. Continue reading for a comprehensive list of adverse effects.

Applies to glycerol phenylbutyrate: oral solution.

Serious side effects

Along with its needed effects, glycerol phenylbutyrate may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking glycerol phenylbutyrate:

More common

  • Black, tarry stools
  • bleeding gums
  • blood in the urine or stools
  • chills
  • confusion
  • continuing nausea or vomiting
  • cough
  • decreased urination
  • dizziness
  • drowsiness
  • dry mouth
  • fainting
  • fever
  • heartburn
  • increase in heart rate
  • increase in the frequency of seizures
  • lightheadedness
  • loss of appetite
  • lower back or side pain
  • muscle tremors
  • painful or difficult urination
  • pale skin
  • pinpoint red spots on the skin
  • rapid breathing
  • rapid, deep breathing
  • restlessness
  • sore throat
  • stomach cramps
  • sunken eyes
  • swollen glands
  • thirst
  • troubled breathing with exertion
  • ulcers, sores, or white spots in the mouth
  • unusual bleeding or bruising
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • wrinkled skin

Other side effects

Some side effects of glycerol phenylbutyrate may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

  • Agitation
  • bloated or full feeling
  • constipation
  • diarrhea
  • excess air or gas in the stomach or bowels
  • headache
  • irritability
  • passing gas
  • rash
  • stomach pain
  • stuffy or runny nose
  • upper abdominal or stomach pain

Less common

Incidence not known

  • Abnormal body, skin, hair, and urine odor
  • burning sensation in the mouth
  • dry heaves
  • gagging
  • loss of or change in taste

For Healthcare Professionals

Applies to glycerol phenylbutyrate: oral liquid.


The most frequently reported side effects included diarrhea, flatulence, and headache.[Ref]

Nervous system

Very common (10% or more): Headache (14%), dizziness[Ref]


Very common (10% or more): Diarrhea (16%), flatulence (14%), upper abdominal pain (pediatric patients), nausea , vomiting

Common (1% to 10%): Abdominal pain (adults), dyspepsia

Postmarketing reports: Retching, gagging, burning sensation in mouth[Ref]


Very Common (10% or more): Decreased appetite, hyperammonemia[Ref]


Common (1% to 10%): Fatigue[Ref]


Very common (10% or more): Rash (pediatric patients)

Postmarketing reports: Abnormal body odor, including from skin, hair, and urine[Ref]


1. "Product Information. Ravicti (glycerol phenylbutyrate)." Hyperion Therapeutics Inc (2013):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.