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Procysbi Side Effects

Generic Name: cysteamine

Note: This page contains side effects data for the generic drug cysteamine. It is possible that some of the dosage forms included below may not apply to the brand name Procysbi.

In Summary

Common side effects of Procysbi include: lethargy, vomiting, and anorexia. Other side effects include: skin rash. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to cysteamine: oral capsule, oral capsule delayed release

As well as its needed effects, cysteamine (the active ingredient contained in Procysbi) may cause unwanted side effects that require medical attention.

Major Side Effects

If any of the following side effects occur while taking cysteamine, check with your doctor immediately:

More common:
  • Abdominal or stomach pain
  • diarrhea
  • drowsiness
  • fever
  • loss of appetite
  • nausea or vomiting
  • skin rash
Less common:
  • Confusion
  • dizziness
  • headache
  • mental depression
  • sore throat
  • trembling
  • Convulsions
  • increased thirst
  • unusual tiredness or weakness
Incidence not known:
  • Blistering, peeling, or loosening of the skin
  • blurred or double vision
  • bone lesions
  • bulging soft spot on head of an infant
  • change in the ability to see colors, especially blue or yellow
  • chills
  • continuing ringing or buzzing or other unexplained noise in the ears
  • cough
  • eye pain
  • hearing loss
  • itching
  • joint or muscle pain
  • loss of appetite
  • loss of vision
  • pain behind the eyes
  • pain in the legs
  • pain with eye movement
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • reddish purple lines on the arms, face, legs, trunk, or groin
  • severe headache
  • sore throat
  • sores, ulcers, or white spots in the mouth or on the lips

Minor Side Effects

Some cysteamine side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

Less common:
  • Breath odor
  • constipation
  • hives or welts
  • redness of the skin
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • weight loss

For Healthcare Professionals

Applies to cysteamine: oral capsule, oral delayed release capsule


The most common adverse events were vomiting, abdominal pain, nausea, anorexia, fever, diarrhea, lethargy, headache, and rash.[Ref]


Very common (10% or more): Vomiting (35%), diarrhea (16%)
Common (1% to 10%): Nausea, bad breath, abdominal pain, dyspepsia
Uncommon (0.1% to 1%): Gastrointestinal ulceration and bleeding, constipation, gastroenteritis, duodenitis[Ref]


Very common (10% or more): Anorexia (31%)
Uncommon (0.1% to 1%): Dehydration[Ref]

Nervous system

Very common (10% or more): Lethargy (11%)
Common (1% to 10%): Dizziness, headache, encephalopathy
Uncommon (0.1% to 1%): Somnolence, seizures, convulsions, ataxia, confusion, tremor, hyperkinesia, jitteriness
Postmarketing reports: Benign intracranial hypertension with papilledema[Ref]


Very common (10% or more): Fever (22%)
Common (1% to 10%): Fatigue, asthenia
Uncommon (0.1% to 1%): Decreasing hearing[Ref]


Common (1% to 10%): Rash, skin odor
Uncommon (0.1% to 1%): Hair color changes, skin fragility (molluscoid pseudomotor on elbows)
Frequency not reported: Urticaria
Postmarketing reports: Skin lesions, skin striae, skin fragility[Ref]

Cases of Ehlers-Danlos like syndrome and vascular disorders on elbows have been reported in children chronically treated with high doses of different cysteamine preparations. In cases where histopathological examination of the skin was performed, the results suggested angioendotheliomatosis.[Ref]


Common (1% to 10%): Abnormal liver function
Frequency not reported: Elevated alkaline phosphatase[Ref]


Uncommon (0.1% to 1%): Hypertension[Ref]


Uncommon (0.1% to 1%): Abnormal urine odor[Ref]


Uncommon (0.1% to 1%): Leukopenia, anemia[Ref]


Uncommon (0.1% to 1%): Anaphylactic reaction[Ref]


Uncommon (0.1% to 1%): Joint hyperextension, leg pain, genu valgum, osteopenia, compression fracture, scoliosis
Postmarketing reports: Molluscoid pseudotumors[Ref]


Uncommon (0.1% to 1%): Nervousness, abnormal thinking, depression, emotional lability, hallucinations, nightmares[Ref]


Uncommon (0.1% to 1%): Nephrotic syndrome, interstitial nephritis, renal failure[Ref]

Cases of nephrotic syndrome have been reported within 6 months of starting therapy with progressive recovery after treatment discontinuation. In some cases, histology showed a membranous glomerulonephritis of the renal allograft and hypersensitivity interstitial nephritis.[Ref]


1. "Product Information. Procysbi (cysteamine)." Raptor Pharmaceutical Corporation, Novato, CA.

2. Cerner Multum, Inc. "Australian Product Information." O 0

3. "Product Information. Cystagon (cysteamine)." Mylan Pharmaceuticals, Morgantown, WV.

4. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

It is possible that some side effects of Procysbi may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

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. 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.