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Sapropterin Side Effects

Medically reviewed by Last updated on Jun 16, 2023.

Applies to sapropterin: oral powder for solution, oral tablet, oral tablet disintegrating.

Serious side effects of Sapropterin

Along with its needed effects, sapropterin 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 sapropterin:

More common

Incidence not known

  • Burning feeling in the chest or stomach
  • cough
  • difficulty with swallowing
  • dizziness
  • fast heartbeat
  • fidgeting or moving around too much
  • heartburn
  • indigestion
  • pain or burning in the throat
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • skin rash, hives, or itching
  • sores, ulcers, or white spots on lips or tongue or inside the mouth
  • stomach upset
  • talking too much
  • tenderness in the stomach area
  • tightness in the chest
  • trouble swallowing
  • unusual tiredness or weakness

Other side effects of Sapropterin

Some side effects of sapropterin 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

Less common

  • Stuffy nose

For Healthcare Professionals

Applies to sapropterin: oral powder for reconstitution, oral tablet, oral tablet soluble.


The more commonly reported adverse effects include headache, rhinorrhea, pharyngolaryngeal pain, diarrhea, vomiting, cough, and nasal congestion.[Ref]

Nervous system

Two cases of hyperactivity have been received during the postmarketing period; in 1 case, the patient had inadvertently received an overdose of this drug.[Ref]

Very common (10% or more): Headache (15%)

Common (1% to 10%): Dizziness

Frequency not reported: Convulsions, exacerbation of convulsions, overstimulation

Postmarketing reports: Hyperactivity[Ref]


Very common (10% or more): Rhinorrhea (11%), pharyngolaryngeal pain (10%)

Common (1% to 10%): Cough, nasal congestion, pharyngitis, upper respiratory tract infection

Frequency not reported: Respiratory failure

Postmarketing reports: Pharyngitis[Ref]


Not all patients respond to therapy; in clinical trials, 25% to 44% of pediatric phenylketonuria (PKU) patients receiving 20 mg/kg/day did not respond to therapy and 80% of adult and pediatric PKU patients receiving 10 mg/kg/day did not respond to therapy.[Ref]

Very common (10% or more): Low phenylalanine levels, non-response to therapy

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


Common (1% to 10%): Diarrhea, vomiting, nausea, abdominal pain, upper abdominal pain

Frequency not reported: Gastrointestinal bleeding, esophageal stricture, esophageal ulcer, gastric ulcer, bleeding

Postmarketing reports: Oropharyngeal pain, esophageal pain, gastritis, dyspepsia, abdominal pain, nausea, vomiting[Ref]


Frequency not reported: Myocardial infarction[Ref]


Common (1% to 10%): Peripheral edema

Frequency not reported: Contusion, postprocedural bleeding, pyrexia[Ref]


Common (1% to 10%): Agitation

Frequency not reported: Irritability


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


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


Postmarketing reports: Hypersensitivity reactions (including serious allergic reactions, anaphylaxis, rash)[Ref]


Frequency not reported: Rash[Ref]


Frequency not reported: Increased GGT[Ref]


1. Product Information. Kuvan (sapropterin). BioMarin Pharmaceutical Inc. 2007.

2. Cerner Multum, Inc. UK Summary of Product Characteristics.

3. Cerner Multum, Inc. Australian Product Information.

4. Dubois EA, Cohen AF. Sapropterin. Br J Clin Pharmacol. 2010;69:576-7.

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.