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Kuvan Side Effects

Generic name: sapropterin

Medically reviewed by Last updated on Feb 17, 2024.

Note: This document contains side effect information about sapropterin. Some dosage forms listed on this page may not apply to the brand name Kuvan.

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

Serious side effects of Kuvan

Along with its needed effects, sapropterin (the active ingredient contained in Kuvan) 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

Other side effects of Kuvan

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

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

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

Common (1% to 10%): Dizziness

Frequency not reported: Convulsions, exacerbation of convulsions, overstimulation

Postmarketing reports: Hyperactivity[Ref]

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): 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]


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

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


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

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

3. Cerner Multum, Inc. "Australian Product Information."

4. Dubois EA, Cohen AF (2010) "Sapropterin." Br J Clin Pharmacol, 69, p. 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.