Applies to sodium phenylbutyrate: oral packet, oral pellet, oral powder, oral tablet.

Serious side effects

Along with its needed effects, sodium 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 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

• Absent, missed, or irregular menstrual periods
• black, tarry stools
• bleeding gums
• bloating
• blood in the urine or stools
• bone pain
• burning, tingling, numbness or pain in the hands, arms, feet, or legs
• chest pain or tightness
• chills
• constipation
• cough
• darkened urine
• discouragement
• dizziness
• fainting
• fast heartbeat
• feeling sad or empty
• fever
• headache
• indigestion
• irritability
• joint pain, stiffness, or swelling
• large, flat, blue or purplish patches in the skin
• loss of appetite
• loss of interest or pleasure
• mood changes
• muscle pain, cramps, or twitching
• numbness or tingling in hands, feet, or lips
• pains in stomach, side, or abdomen, possibly radiating to the back
• painful or difficult urination
• pinpoint red spots on the skin
• rectal bleeding
• seizures
• sensation of pins and needles
• severe or continuing stomach pain
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• stabbing pain
• stopping of menstrual bleeding
• swelling of the feet or lower legs
• swollen or painful glands
• trouble breathing
• trouble concentrating
• trouble sleeping
• uneven heartbeat
• unusual bleeding or bruising
• yellow eyes or skin

Rare

• Dryness of the mouth
• fast, slow, or irregular heartbeat
• increased thirst
• swelling of the face
• unusual weight gain
• weak pulse

Other side effects

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

• Body odor
• burning feeling in the chest or stomach
• decreased appetite
• increased weight
• skin rash
• stomach pain or upset

Incidence not known

• Change in taste
• loss of taste

For Healthcare Professionals

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

General

Causality of adverse effects is sometimes difficult to determine because they may result from either the underlying disease, the patient's restricted diet, intercurrent illness, or the drug itself.^[Ref]

Endocrine

Very common (10% or more): Amenorrhea/menstrual dysfunction (23%)^[Ref]

Metabolic

Very common (10% or more): Acidosis (14%), hypoalbuminemia (11%)

Common (1% to 10%): Alkalosis, decreased appetite, hyperchloremia, hypophosphatemia, decreased total protein, hyperuricemia, hyperphosphatemia, hypernatremia, hypokalemia, increased weight^[Ref]

Cardiovascular

Common (1% to 10%): Edema

Uncommon (0.1% to 1%): Arrhythmia^[Ref]

Dermatologic

Common (1% to 10%): Rash, body odor^[Ref]

Gastrointestinal

Common (1% to 10%): Abdominal pain, nausea, vomiting, constipation, dysgeusia

Uncommon (0.1% to 1%): Pancreatitis, rectal bleeding/hemorrhage, peptic ulcer, gastritis^[Ref]

Hematologic

Common (1% to 10%): Anemia, leukopenia, leukocytosis, thrombocytopenia, thrombocytosis

Uncommon (0.1% to 1%): Aplastic anemia, ecchymosis^[Ref]

Hepatic

Common (1% to 10%): Increased alkaline phosphatase, increased liver transaminases, hyperbilirubinemia^[Ref]

Nervous system

Common (1% to 10%): Syncope, headache, bad taste/taste aversion

Frequency not reported: Somnolence, fatigue, lightheadedness, hypoacusis, disorientation, impaired memory, exacerbation of preexisting neuropathy^[Ref]

Psychiatric

Common (1% to 10%): Depression, irritability^[Ref]

Renal

Common (1% to 10%): Renal tubular acidosis^[Ref]