Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 2/23/2022
Procysbi Side Effects Center

What Is Procysbi?

Procysbi (cysteamine bitartrate) is a cystine depleting agent used to treat a rare genetic condition called nephropathic cystinosis in patients over the age of six years old.

What Are Side Effects of Procysbi?

Common side effects of Procysbi include:

Dosage for Procysbi

Procysbi should be prescribed by a physician experienced in management of nephropathic cystinosis. Procysbi capsules should be swallowed whole or after sprinkling on food or in recommended liquids. The total daily dose of Procysbi is 1.3 gram/m2/day in two divided doses, every 12 hours. Procysbi should be taken at least two hours after a meal and at least 30 minutes before eating.

What Drugs, Substances, or Supplements Interact with Procysbi?

Drug interactions with Procysbi have not been described, but this does not mean that these may not develop.

Procysbi During Pregnancy and Breastfeeding

Procysbi has not been studied in pregnant women and should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Breastfeeding is not recommended while taking Procysbi.

Additional Information

Procysbi (cysteamine bitartrate) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Procysbi Consumer Information

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Call your doctor at once if you have any of these side effects (some of these may be caused by your cystinosis disorder and not by this medicine):

  • depressed mood, extreme drowsiness;
  • a seizure;
  • unusual bruising or streaks on the skin;
  • bone pain, abnormal joint movement;
  • an electrolyte imbalance--increased thirst or urination, confusion, constipation, leg cramps, irregular heartbeats, tingly feeling;
  • increased pressure inside the skull--severe headaches, ringing in your ears, dizziness, vision problems, pain behind your eyes; or
  • stomach problems--pain, nausea, vomiting, loss of appetite, coughing up blood or vomit that looks like coffee grounds.

Common side effects may include:

  • drowsiness, feeling tired;
  • stomach pain, nausea, vomiting, loss of appetite, diarrhea;
  • unusual breath odor or skin odor;
  • rash;
  • fever; or
  • headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Procysbi (Cysteamine Bitartrate Delayed-release Capsules)


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Procysbi Professional Information


The following adverse reactions are also discussed in other sections of the labeling:

  • Ehlers-Danlos-like Syndrome [see WARNINGS AND PRECAUTIONS]
  • Gastrointestinal (GI) Ulcers and Bleeding [see WARNINGS AND PRECAUTIONS]
  • Central Nervous System Symptoms [see WARNINGS AND PRECAUTIONS]
  • Leukopenia and/or Elevated Phosphatase Levels [see WARNINGS AND PRECAUTIONS]
  • Benign Intracranial Hypertension [see WARNINGS AND PRECAUTIONS]

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

The data described below reflect exposure to cysteamine in 345 patients with nephropathic cystinosis (246 patients receiving immediate-release cysteamine as cysteamine hydrochloride or phosphocysteamine, and 80 patients receiving PROCYSBI) in open-label clinical trials.

Clinical Trials Experience With PROCYSBI In Patients Switched From Immediate-Release Cysteamine Bitartrate

Sixty-two patients with nephropathic cystinosis (38 males and 24 females) received PROCYSBI in two clinical trials at doses ranging from 0.29 grams/m2 per day to 2.19 grams/m2 per day [see Clinical Studies]. All patients were switched from immediate-release cysteamine to PROCYSBI. Forty-three patients, ages 6 to 26 years old, received PROCYSBI in an 8-week, open-label, randomized, cross-over trial comparing PROCYSBI to immediate-release cysteamine bitartrate. Forty of 43 patients continued PROCYSBI treatment in an open-label extension trial (36 patients were treated with PROCYSBI for longer than 2 years, and 20 patients were treated for longer than 5 years). An additional 19 patients (6 renal transplanted patients and 13 patients aged 2 to 6 years) were enrolled directly into this trial (12 patients were treated with PROCYSBI for longer than 2 years, and 9 patients were treated for longer than 5 years).

In the open-label, randomized, cross-over trial, a higher incidence of adverse reactions was reported in patients during the PROCYSBI treatment period compared with the immediate-release cysteamine bitartrate treatment period (see Table 2). Other significant adverse reactions reported during clinical trials included hypersensitivity reactions, including anaphylaxis.

Table 2: Adverse Reactions in ≥5% of Patients with Nephropathic Cystinosis in a Randomized, Cross-Over Trial

Adverse ReactionImmediate-Release CysteaminePROCYSBI
(n = 41)
(n = 43)
Abdominal pain/discomfort014
Anorexia/loss of appetite52

In the open-label extension trial (N=59), the most commonly reported adverse reactions (>15%) were vomitin g, headache, diarrhea, nausea, conjunctivitis, influenza, gastroenteritis, nasopharyngitis, abdominal pain, dehydration, ear infection, upper respiratory tract infection, fatigue, arthralgia, cough, and pain in extremity.

Clinical Trials Experience With PROCYSBI In Cysteamine-Naïve Patients

Seventeen cysteamine-naïve patients (fifteen patients between the ages of 1 and 5 years, one 9-year old and one 22-year old) received PROCYSBI in an open-label clinical trial [see Clinical Studies]. Serious adverse reactions occurring in at least 2 patients (>10%) were: gastroenteritis/viral gastroenteritis (n=6), vomiting (n=4), and electrolyte imbalance (n=2). Three patients with serious adverse reactions of gastroenteritis also had dehydration. Common adverse reactions reported at a frequency of >10% (occurring in at least 2 patients) are shown in Table 3.

Table 3: Adverse Reactions in >10% of Patients with Nephropathic Cystinosis Naïve to Cysteamine Treatment in an Open-Label Trial

Adverse ReactionPROCYSBI
N = 17
n (%)
Vomiting13 (77)
Gastroenteritis/viral gastroenteritis9 (53)
Diarrhea6 (35)
Breath odor4 (24)
Nausea3 (18)
Electrolyte imbalance2 (12)
Headache2 (12)

Clinical Trials Experience With Immediate-Release Cysteamine

The most frequent adverse reactions involved the gastrointestinal and central nervous systems and were especially prominent at the initiation of cysteamine therapy. Most patients were able to resume therapy at lower doses. The most common reactions (>5%) were vomiting, anorexia, fever, diarrhea, lethargy, and rash. Other adverse reactions included nausea, bad breath, abdominal pain, headache, dizziness, and urticaria.

Withdrawals due to intolerance, vomiting, anorexia, lethargy, and fever occurred more frequently in those patients receiving 1.95 grams/m2 per day as compared with 1.3 grams/m2 per day of immediate-release cysteamine bitartrate.

Postmarketing Experience

The following adverse reactions have been identified during post-approval use of immediate-release cysteamine bitartrate. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.

  • Musculoskeletal: Joint hyperextension, leg pain, osteopenia, compression fracture, scoliosis, genu valgum [see WARNINGS AND PRECAUTIONS].
  • Skin: Erythema multiforme bullosa, toxic epidermal necrolysis, Ehlers-Danlos-like syndrome, molluscoid pseudotumors, skin striae, skin fragility [see WARNINGS AND PRECAUTIONS].
  • Central Nervous System: seizures, lethargy, somnolence, depression and encephalopathy [see WARNINGS AND PRECAUTIONS], benign intracranial hypertension (or PTC) and/or papilledema [see WARNINGS AND PRECAUTIONS].

Read the entire FDA prescribing information for Procysbi (Cysteamine Bitartrate Delayed-release Capsules)

© Procysbi Patient Information is supplied by Cerner Multum, Inc. and Procysbi Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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