Buphenyl Side Effects

Generic Name: sodium phenylbutyrate

Note: This page contains information about the side effects of sodium phenylbutyrate. Some of the dosage forms included on this document may not apply to the brand name Buphenyl.

Not all side effects for Buphenyl may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to sodium phenylbutyrate: oral powder, oral tablet, oral tablet enteric coated

Along with its needed effects, sodium phenylbutyrate (the active ingredient contained in Buphenyl) 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 sodium phenylbutyrate:

More common
  • Change in the frequency of breathing
  • lack of or irregular menstruation
  • lower back, side, or stomach pain
  • mood or mental changes
  • muscle pain or twitching
  • nausea or vomiting
  • nervousness or restlessness
  • swelling of the feet or lower legs
  • unpleasant taste
  • unusual tiredness or weakness
Less common
  • Chills
  • fever
  • joint pain
  • sore throat
  • unusual bleeding or bruising
  • Convulsions (seizures)
  • dizziness
  • dryness of the mouth
  • fast, slow, or irregular heartbeat
  • increased blood pressure
  • increased thirst
  • irritability
  • muscle cramps
  • rectal bleeding
  • swelling of the face
  • unusual weight gain
  • weak pulse

Some side effects of sodium 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:

Less common
  • Changes in taste
  • decreased appetite
  • strong body odor
  • Abdominal or stomach pain
  • constipation
  • fainting
  • headache
  • mental depression
  • skin rash

For Healthcare Professionals

Applies to sodium phenylbutyrate: oral powder for reconstitution, oral tablet


Frequency not reported: Aplastic anemia, ecchymoses


Frequency not reported: Arrhythmia, edema


Frequency not reported: Rash


Frequency not reported: Abdominal pain, gastritis, nausea and vomiting; constipation, rectal bleeding, peptic ulcer disease, pancreatitis


Very common (10% or more): Amenorrhea/menstrual dysfunction (23%)


Common (1% to 10%): Decreased appetite (4%), body odor (3%), bad taste or taste aversion (3%)
Frequency not reported: Weight gain

Nervous system

Frequency not reported: Headache, syncope, neurotoxicity (manifested predominantly with somnolence, fatigue, and lightheadedness; and less frequently with headache, dysgeusia, hypoacusis, disorientation, impaired memory, and exacerbation of a pre-existing neuropathy)


Frequency not reported: Depression


Frequency not reported: Renal tubular acidosis


Laboratory Adverse Event in Patients with urea cycle disorders (UCDs):
Very common (10% or more): Acidosis (14%), hypoalbuminemia (11%)
Common (1% to 10%): Anemia (9%), alkalosis (7%), hyperchloremia (7%), hypophosphatemia (6%), increased alkaline phosphatase (6%), increased liver transaminases (4%), leukopenia (4%), leukocytosis (4%), decreased total protein (3%), thrombocytopenia (3%), hyperuricemia (2%), hyperphosphatemia (2%), hypernatremia (1%), hypokalemia (1%), hyperbilirubinemia (1%), thrombocytosis (1%)

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. Drugs.com does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.