Cystagon (cysteamine bitartrate)
An approved treatment for Cystinosis.
The same compound appears under different names depending on the context. Here is how to identify Cysteamine bitartrate wherever you encounter it, plus the key facts at a glance.
- Generic name
- Cysteamine bitartrate
- Brand name
- Cystagon
- Drug class
- Cystine-depleting agent
- Manufacturer
- Mylan (Viatris)
- How it's taken
- Capsules 4 times a day, starting at a fraction of the full dose and raising it over 4 to 6 weeks.
The original immediate-release cysteamine capsule, taken 4 times a day, approved August 15, 1994, for nephropathic cystinosis in children and adults.
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Where Cysteamine bitartrate fits
The original treatment for nephropathic cystinosis; Procysbi is a twice-a-day alternative.
How Cysteamine bitartrate works
Cysteamine enters the lysosome and reacts with cystine, making compounds that can leave the lysosome. That lowers the cystine that would otherwise form crystals and damage the kidneys and other organs.
Mechanism: Lowers cystine trapped inside cells' lysosomes
Side effects and safety
Warnings include severe skin rashes, nervous system symptoms such as seizures, tiredness and depression, and stomach and bowel ulcers and bleeding. The most common side effects in its label were vomiting (35%), loss of appetite (31%), fever (22%), diarrhea (16%), lethargy (11%) and rash (7%).
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Cysteamine bitartrate
Capsules 4 times a day, starting at a fraction of the full dose and raising it over 4 to 6 weeks. The dose is based on body size, aiming for a white blood cell cystine level below 1 nmol half-cystine per mg protein. Young children should not swallow whole capsules; the contents can be sprinkled on food.
Availability and cost
Only available as the brand-name product.
Development history
Approved by the FDA on August 15, 1994.
Explore Cystinosis trials
Other Cystinosis treatments
Common questions about Cysteamine bitartrate
▸What is Cysteamine bitartrate (Cystagon)?
The original immediate-release cysteamine capsule, taken 4 times a day, approved August 15, 1994, for nephropathic cystinosis in children and adults.
▸How does Cysteamine bitartrate work?
Cysteamine enters the lysosome and reacts with cystine, making compounds that can leave the lysosome. That lowers the cystine that would otherwise form crystals and damage the kidneys and other organs.
▸What are the side effects of Cysteamine bitartrate?
Warnings include severe skin rashes, nervous system symptoms such as seizures, tiredness and depression, and stomach and bowel ulcers and bleeding. The most common side effects in its label were vomiting (35%), loss of appetite (31%), fever (22%), diarrhea (16%), lethargy (11%) and rash (7%).
▸How is Cysteamine bitartrate taken?
Capsules 4 times a day, starting at a fraction of the full dose and raising it over 4 to 6 weeks. The dose is based on body size, aiming for a white blood cell cystine level below 1 nmol half-cystine per mg protein. Young children should not swallow whole capsules; the contents can be sprinkled on food.
▸Is Cysteamine bitartrate FDA approved?
Yes, Cysteamine bitartrate (Cystagon) is FDA approved (1994) for the treatment of Cystinosis.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed · 2021-08. CYSTAGON (cysteamine bitartrate) capsules: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f495b76d-96c6-48e5-8fa3-30a4336628eb
- NCBI Bookshelf, GeneReviews · 2025-08. Cystinosis. https://www.ncbi.nlm.nih.gov/books/NBK1400/