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.

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.

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.

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

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 frequently reported side effects included vomiting, abdominal pain/discomfort, headaches, nausea, diarrhea, anorexia/decreased appetite, breath odor, fatigue, dizziness, skin odor, and rash.


Frequency not reported: Hypertension


Common (1% to 10%): Rash
Frequency not reported: Urticaria, skin odor
Postmarketing reports: Skin lesions, skin striae, skin fragility


Very common (10% or more): Vomiting, diarrhea, anorexia, diarrhea
Frequency not reported: Gastrointestinal ulceration and bleeding, nausea, bad breath, abdominal pain, dyspepsia, constipation, gastroenteritis, duodenitis


Frequency not reported: Abnormal urine odor, interstitial nephritis


Frequency not reported: Leukopenia, anemia


Frequency not reported: Elevated alkaline phosphatase, abnormal liver function


Frequency not reported: Dehydration


Postmarketing reports: Molluscoid pseudotumors, joint hyperextension, leg pain, genu valgum, osteopenia, compression fracture, scoliosis

Nervous system

Very common (10% or more): Lethargy
Frequency not reported: Somnolence, encephalopathy, seizures, dizziness, headache, ataxia, confusion, tremor, hyperkinesia, decreasing hearing, jitteriness
Postmarketing reports: Benign intracranial hypertension with papilledema


Very common (10% or more): Fever
Frequency not reported: Fatigue


Frequency not reported: Nervousness, abnormal thinking, depression, emotional lability, hallucinations, nightmares


Frequency not reported: Renal failure

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