Cysteamine: uses, dosing, side effects & brands
Cysteamine is a cystine depleting agent sold in the U.S. under 4 brand and generic names, for cystinosis. Below: what the FDA label says, every product that contains it, what the pills look like, and its recall record.
Key facts
- Drug class
- Cystine Depleting Agent
- Treats (across its forms)
- Cystinosis
- Available as
- Capsule · Solution · Oral pellets · Powder, delayed release
- Sold as
- 4 products — Cystagon, Cystadrops and Cystaran, and others
- Prescription?
- Prescription only
- Generic available?
- Not in our catalog
How Cystagon is dosed
From the FDA label for Cystagon (application NDA020392). Other cysteamine products — different forms, different strengths — are dosed differently. Follow the label for the one you were prescribed.
For the management of nephropathic cystinosis, cysteamine therapy should be initiated promptly once the diagnosis is confirmed (i.e., increased white cell cystine). New patients should be started on ¼ to 1/6 of the maintenance dose of CYSTAGON ® . The dose should then be raised gradually over four to six weeks to avoid intolerance. The recommended CYSTAGON ® maintenance dose for children up to age 12 years is 1.30 grams/m 2 /day of the free base, given in four divided doses. Intact CYSTAGON ® capsules should not be administered to children under the age of approximately six years due to the risk of aspiration. CYSTAGON ® capsules may be administered to children under the age of approximately six years by sprinkling the capsule contents over food. Patients over age 12 and over 110 pounds weight should receive 2.0 grams/day, divided four times daily. If a dose is missed, it should be taken as soon as possible. If it is within two hours of the next dose, skip the missed dose and go back to the regular dosing schedule. Do not double dose. When CYSTAGON ® is well tolerated, the goal of therapy is to keep leukocyte cystine levels below 1 nmol/½ cystine/mg protein five to six hours following administration of CYSTAGON ® . Patients with poorer tolerability still receive significant benefit if white cell cystine levels are below 2 nmol/½ cystine/mg protein. The CYSTAGON ® dose can be…
Everything below is the FDA label for Cystagon (capsule). Cysteamine is also sold as solution, oral pellets and powder, delayed release, and those are different medicines to take — follow the label for the one you were prescribed.
Cystagon side effects
In three clinical trials, cysteamine or phosphocysteamine have been administered to 246 children with cystinosis. Causality of side effects is sometimes difficult to determine because adverse effects may result from the underlying disease. The most frequent adverse reactions seen involve the gastrointestinal and central nervous systems. These are especially prominent at the initiation of cysteamine therapy. Temporarily suspending treatment, then gradual re-introduction may be effective in improving tolerance. Adverse reactions were not collected systematically in the NCCS, but were often listed by investigators. The following rates may therefore be underestimated. The most common events (> 5%) were vomiting 35%, anorexia 31%, fever 22%, diarrhea 16%, lethargy 11%, and rash 7%. Less common adverse events are: Body as a whole: Dehydration. Cardiovascular: Hypertension. Digestive: Nausea, bad breath, abdominal pain, dyspepsia, constipation, gastroenteritis, duodenitis, gastrointestinal ulceration and bleeding. Central Nervous System: Somnolence, encephalopathy, headache, seizures, ataxia, confusion, tremor, hyperkinesia, decreasing hearing, dizziness, jitteriness. Psychiatric: Nervousness, abnormal thinking, depression, emotional lability, hallucinations, nightmares. Integumentary: Urticaria. Urogenital: Interstitial nephritis, renal failure (see WARNINGS ). Clinical Laboratory:…
Who shouldn’t take Cystagon
CYSTAGON ® is contraindicated in patients who have developed hypersensitivity to it or to cysteamine or penicillamine.
Cystagon drug interactions
None have been described. CYSTAGON ® can be administered with electrolyte and mineral replacements necessary for management of the Fanconi Syndrome as well as vitamin D and thyroid hormone.
Every cysteamine product we track (4)
Same active ingredient — different manufacturer, form, price and FDA recall record. That last one is what our independent score measures.
| # | Drug | Rating | Type | Form | Generic? | Pharmacy pays | |
|---|---|---|---|---|---|---|---|
| 1 | 66/100 | Prescription | Capsule | No data | — | View → | |
| 2 | Not yet rated | Prescription | Solution | No data | — | View → | |
| 3 | Not yet rated | Prescription | Solution | No data | — | View → | |
| 4 | Not yet rated | Prescription | Capsule | No data | — | View → |
What cysteamine pills look like
Imprint codes, colour and shape from the FDA’s labelling data. Match the imprint on your pill — or search any imprint.
| Imprint | Strength | Colour | Shape | Maker |
|---|---|---|---|---|
| PRO;75;mg | 75 mg | blue | capsule | — |
| CYSTA;50;MYLAN | 50 mg | white | capsule | — |
| CYSTAGON;150;MYLAN | 150 mg | white | capsule | — |
| PRO;25;mg | 25 mg | blue | capsule | — |
Can you crush or split cysteamine?
At least one cysteamineproduct is labelled to be swallowed whole — crushing an extended-release tablet releases the whole day’s dose at once. Which applies depends on the form you were given.
What each cysteamine label says about crushing, splitting and chewingHow long cysteamine keeps
The date on a sealed pack is not the only one: some cysteamine labels start a second clock once the product is opened or mixed, as short as 7 days.
Does cysteamine expire? The in-use limits and storage rules from its labelsWhat people report to the FDA about cysteamine
The FDA Adverse Event Reporting System (FAERS) collects reports from patients and clinicians. It holds 42 reports naming cysteamine, and the FDA flagged 90% of those reports as serious. The effects reported most often — leaving out reports about overdose, misuse or the condition being treated, which dominate the raw list for common medicines:
- diarrhoea4 reports
- nausea4 reports
- vomiting3 reports
- abdominal discomfort2 reports
- abdominal pain upper2 reports
- acidosis2 reports
- dehydration2 reports
- epstein-barr virus test positive2 reports
Read these as a signal, not a rate. A report does not mean cysteamine caused the effect — anyone can file one, and many describe people taking several medicines for several conditions. Crucially there is no denominator: FAERS does not record how many people took the drug, so these counts cannot be turned into “X% of patients” — a bigger number often just means a more widely used or more talked-about drug. Duplicates exist, and publicity drives reporting. For what is actually established, read the FDA label section above.
Source: openFDA drug/event (FAERS), retrieved August 25, 2026.
Related calculators
Frequently asked questions
What is Cystagon?
CYSTAGON ® (cysteamine bitartrate) Capsules for oral administration, contain cysteamine bitartrate, a cystine depleting agent which lowers the cystine content of cells in patients with cystinosis, an inherited defect of lysosomal transport. CYSTAGON ® is the bitartrate salt of cysteamine, an aminothiol, beta-mercaptoethylamine.
What kind of drug is cysteamine?
The FDA classifies cysteamine as a cystine depleting agent. If you are checking whether it is safe to combine with something else, the class is what matters — two drugs from the same class usually should not be stacked.
Can you take cysteamine with other medicines?
It depends on the medicine. We check it against the FDA labels rather than guessing: our interaction checker searches each drug's own label for the other and quotes what it says, naming the section it came from. Run cysteamine against whatever else you take — and remember that a label not naming a drug is not the same as that combination being safe.
What brand names is cysteamine sold under?
We track 4 cysteamine-containing products in the U.S.: Cystagon, Cystadrops, Cystaran and Procysbi. They are the same active ingredient; they differ in form, manufacturer, price and FDA recall record.
What forms does cysteamine come in?
Across the brands we track, cysteamine is currently marketed as capsule, solution, oral pellets and powder, delayed release, per the FDA's National Drug Code Directory. Each form is dosed differently — follow the label for the exact product you were prescribed.
Is there a generic cysteamine?
We do not currently list a generic-labelled cysteamine product. That does not always mean none exists — it means none appears under a generic name in the FDA data we track. Ask your pharmacist.
Cite this page
- APA
- pharmaranks. (2026, July 24). Cysteamine: uses, dosing, side effects & brands. https://pharmaranks.com/drugs/cysteamine
- MLA
- “Cysteamine: uses, dosing, side effects & brands.” pharmaranks, 24 July 2026, https://pharmaranks.com/drugs/cysteamine.
We summarise public FDA and NIH sources — for a clinical claim, cite the primary source we link to as well.
Sources: FDA openFDA drug label, National Drug Code Directory, and Enforcement (recall) database. This page reproduces public FDA data and is not medical advice. Dosing is set by your prescriber.
Read the full FDA label for cysteamine on DailyMed (NIH) ↗.