Cysteamine
Cysteamine is a cystine-depleting agent used to treat nephropathic cystinosis (an inherited disorder that causes a harmful amino acid to build up in cells) and to clear cystine crystal deposits from the cornea of the eye.
🧬 Where this information comes from Click to expand
The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 2 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →
📖 Cysteamine: Patient Information Guide
A plain-language walkthrough of Cysteamine — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.
🎯What it's used for▾
Cysteamine is used across several products and routes to treat cystinosis, a rare inherited disease that causes the amino acid derivative cystine to build up harmfully inside cells.
- Cystagon (oral capsule) — for the management of nephropathic cystinosis (the kidney-affecting form) in children and adults
- Procysbi (oral delayed-release capsule and oral powder) — for the treatment of nephropathic cystinosis in adults and children 1 year of age and older
- Cystadrops (ophthalmic eye drops) — for the treatment of corneal cystine crystal deposits in adults and children with cystinosis
- Cystaran (ophthalmic eye drops) — for the treatment of corneal cystine crystal accumulation in patients with cystinosis
⚙️How it works▾
Cystinosis is caused by a defect in the transporter that normally moves cystine out of lysosomes — the compartments inside cells that break down waste. Without this transporter working properly, cystine accumulates and forms crystals that damage the kidneys, eyes, muscles, brain, and other organs. Cysteamine is an aminothiol (a sulfur-containing compound) that enters lysosomes and reacts directly with cystine through a chemical exchange reaction, converting it into two smaller molecules — cysteine and a cysteine-cysteamine compound — that can exit the lysosome through an alternate route. This lowers cystine levels throughout the body and helps protect organs from ongoing damage.
💊How it's taken▾
The oral forms are taken on a regular schedule around the clock. Cystagon is generally taken four times daily (every 6 hours). Procysbi (both the delayed-release capsule and oral granule form) is taken every 12 hours, on an empty stomach — avoiding food for at least 2 hours before and 30 minutes after each dose, and avoiding alcohol and grapefruit juice. Eye drops are applied directly into each eye during waking hours: Cystadrops four times a day, Cystaran every waking hour.
- Doses are adjusted based on regular blood tests that measure white blood cell cystine levels
- If you miss a dose of Cystagon, take it as soon as you remember — but if it is within 2 hours of your next dose, skip it and return to your normal schedule; do not double up
- Always follow your prescriber's specific instructions, as dosing is individualized
🤒Side effects — in detail▾
The most commonly reported side effects involve the stomach and nervous system, and they can be especially noticeable when treatment is first started.
- Nausea and vomiting
- Diarrhea
- Stomach pain or discomfort
- Unpleasant breath or body odor
- Headache
- Fatigue
- Skin rash
- Loss of appetite
Serious reactions — including severe skin blistering, gastrointestinal bleeding, seizures, or signs of increased pressure in the brain — should prompt you to contact your doctor or seek medical care right away. Your doctor will monitor your blood counts and certain enzyme levels regularly while you are on this medication.
⚠️Warnings & precautions▾
- Ehlers-Danlos-like syndrome: High doses have been linked to unusual skin lesions, stretch marks, bone thinning, fractures, and joint laxity. If these develop, your dose will likely need to be reduced or temporarily stopped.
- Severe skin reactions: Rare but serious blistering skin conditions (erythema multiforme bullosa, toxic epidermal necrolysis) have been reported. If this happens, Procysbi must be permanently discontinued.
- GI ulcers and bleeding: Stomach ulcers and gastrointestinal bleeding have occurred. Alert your doctor to any severe stomach pain, vomiting blood, or black stools.
- Fibrosing colonopathy: A rare condition causing colon scarring has been reported specifically with Procysbi in pediatric and young adult patients. Severe, persistent, or worsening abdominal symptoms should be evaluated promptly. If confirmed, Procysbi must be permanently stopped.
- Central nervous system effects: Seizures, confusion, depression, and encephalopathy have been associated with cysteamine. The medication may also impair the ability to drive or operate machinery.
- Benign intracranial hypertension: Raised pressure inside the skull — with symptoms like persistent headache, vision changes, ringing in the ears, or eye pain — has been reported. If confirmed, Procysbi must be stopped.
- Low white blood cell counts and elevated alkaline phosphatase: These are generally reversible, but regular blood monitoring is needed.
🔀What it interacts with▾
A few important interactions to know about when taking cysteamine:
- Antacids or supplements containing bicarbonate or carbonate — can cause Procysbi to release cysteamine too early, reducing its effectiveness; take Procysbi at least 1 hour apart from these
- Alcohol — can alter the release and pharmacokinetics of Procysbi, affecting both its safety and effectiveness; avoid alcohol while taking Procysbi
- Grapefruit juice — should be avoided with oral cysteamine products; use other fruit juices or water instead
- Electrolyte supplements, vitamin D, thyroid hormone — these are often used alongside Procysbi to manage Fanconi syndrome and can be taken together safely
This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.
📋Before taking it▾
- Do not take cysteamine if you have had a serious allergic reaction — including anaphylaxis — to cysteamine or to penicillamine
- Pregnancy: Animal studies showed cysteamine caused serious birth defects at high doses; Cystadrops should be used during pregnancy only if the potential benefit clearly outweighs the risk to the fetus
- Breastfeeding: It is unknown whether cysteamine passes into human breast milk; discuss the risks and benefits with your doctor
- Children: Procysbi is approved for children 1 year and older; Cystagon capsules should not be swallowed whole by children under about 6 years old — sprinkle the capsule contents on food instead
- Kidney impairment: Higher cysteamine levels may build up in people with moderate to severe kidney problems when taking Procysbi; your prescriber will consider this when setting your dose
🚑If you take too much▾
Taking too much cysteamine can cause nausea, vomiting, and dehydration. In a reported case involving a young child who accidentally took a large amount of immediate-release cysteamine, vomiting and dehydration occurred and were managed with fluids in the hospital — the child fully recovered. If an overdose is suspected, supportive care (including breathing and heart monitoring) should be provided; there is no specific antidote, but hemodialysis may be considered since cysteamine is only moderately bound to blood proteins.
📡Pharmacodynamics — effects in the body▾
Cysteamine works by lowering the concentration of cystine inside white blood cells — a measure used to track how well the medication is working. After a dose of Procysbi, white blood cell cystine levels reach their lowest point at around 3.5 hours post-dose, closely following the peak drug level in the blood, and return to baseline by about 12 hours. For Cystagon, the lowest cystine levels occur at roughly 1 hour after dosing. The goal of treatment is to keep white blood cell cystine concentrations below a defined threshold, and doses are adjusted based on regular monitoring of these levels.
🔬Pharmacokinetics — how your body processes it▾
Procysbi is a delayed-release formulation, so cysteamine reaches peak blood levels at about 3 hours after a dose — roughly 2.5 times longer than with immediate-release Cystagon. Cysteamine is moderately bound to blood proteins (about 52%), primarily albumin. The half-life (the time for blood levels to drop by half) is about 4 hours with Procysbi compared to about 90 minutes with immediate-release cysteamine. In patients with moderate to severe kidney impairment, cysteamine levels can be significantly higher than in people with normal kidney function, so monitoring and possible dose adjustment are important. For the eye drop forms, systemic absorption is negligible — the total daily ophthalmic dose represents less than 4% of the typical oral daily dose.
📦How to store it▾
store PROCYSBI delayed-release capsules and PROCYSBI delayed-release oral granules in a refrigerator, 2°C to 8°C (36°F to 46°F). Dispense in original packaging. Protect from light and moisture.
📄 Written from Cysteamine’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →
🩺 Pharmacist Counseling Corner
Quick, plain-English answers to the questions patients ask most about Cysteamine — the kind of thing our pharmacy team would talk through with you at the counter.
What exactly is cystinosis, and why do I need this medication for life? ▾
How do I know if the medication is working? ▾
Why does my breath or body smell different since starting cysteamine? ▾
Are there any foods or drinks I need to avoid? ▾
What side effects should make me call my doctor right away? ▾
I'm using the eye drops — are they different from the oral medication? ▾
Is Cysteamine available over the counter? ▾
When was Cysteamine first available? ▾
Who makes Cysteamine? ▾
💬 Answers drafted from Cysteamine’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →
🧰 Keep exploring
💊 How Cysteamine comes
Cysteamine is available in 4 forms. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.
Delayed-release capsule
How this form is used
- Procysbi is indicated for the treatment of nephropathic cystinosis in adults and children 1 year of age and older
- Procysbi delayed-release capsules should be swallowed whole — do not crush or chew the capsule or its contents
- Procysbi capsules should be taken with fruit juice (except grapefruit juice) or water; do not eat for at least 2 hours before and 30 minutes after taking Procysbi
- Procysbi should be taken at least 1 hour before or 1 hour after medications containing bicarbonate or carbonate
- Avoid alcohol while taking Procysbi; for patients who cannot swallow capsules, speak with your prescriber about alternative preparation options
Eye drops
How this form is used
- Cystadrops is indicated for the treatment of corneal cystine crystal deposits in adults and children with cystinosis
- Cystaran is indicated for the treatment of corneal cystine crystal accumulation in patients with cystinosis
- Cystadrops: instill one drop in each eye 4 times a day during waking hours; discard the bottle 7 days after first opening
- Cystaran: instill one drop in each eye every waking hour; discard after 1 week of use
- Do not touch the dropper tip to the eyelids, surrounding areas, or any surface to avoid contamination
- Cystadrops: if using other eye drops at the same time, wait at least 10 minutes between products; apply eye ointments last
Oral powder
How this form is used
- Procysbi oral granules are used for the treatment of nephropathic cystinosis in adults and children 1 year of age and older
- Procysbi granules should not be crushed or chewed — sprinkle and mix them in applesauce, berry jelly, or fruit juice (except grapefruit juice)
- Procysbi granules should be taken at least 1 hour before or 1 hour after medications containing bicarbonate or carbonate
- Do not eat for at least 2 hours before and 30 minutes after taking Procysbi granules; avoid alcohol
- Procysbi granules can also be administered via gastrostomy tube — follow the full prescribing instructions for preparation
Capsule
How this form is used
- Cystagon is used for the management of nephropathic cystinosis in children and adults
- Cystagon is typically taken four times daily (every 6 hours)
- Cystagon capsules should not be swallowed whole by children under approximately 6 years old — sprinkle capsule contents over food instead
- If a dose is missed, take it as soon as possible; if it is within two hours of the next dose, skip the missed dose and resume the regular schedule — do not double dose
- Patients switching from cysteamine hydrochloride or phosphocysteamine solutions can be transferred to equivalent doses of Cystagon
📊 Cysteamine across the U.S. market
How Cysteamine appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.
FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
Also listed with the FDA, not a patient dose form: Powder (8) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.
Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.
📈 How widely Cysteamine is used
A general measure of how commonly Cysteamine is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.
Think of this as a proxy for how widely Cysteamine is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.
How commonly is Cysteamine prescribed? Of the 1,596 medications we measure, Cysteamine ranks #1,302 by Medicaid prescriptions — more than 18% of them.
Utilization by Cysteamine product
Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.
cysteamine 75 MG Delayed Release Oral Capsule Most dispensed
Summed across the 1 of 1 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1421475
cysteamine 300 MG Delayed Release Oral Granules
Summed across the 1 of 2 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 2284510
cysteamine 4.4 MG/ML Ophthalmic Solution
Summed across the 1 of 3 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1313780
Other Cysteamine products — combination packs and listings not yet matched to a specific clinical product (kept visible so every prescription is accounted for)
Summed across the 1 of 14 listed NDC products with Medicaid activity.
Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.
Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Cysteamine, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 4 of 20 listed Cysteamine NDCs with Medicaid activity.
🔍 Compare Cysteamine products
A representative set of FDA-listed product records for Cysteamine — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)
| Strength | Route | Manufacturer / Labeler | Category ⓘ | Details |
|---|---|---|---|---|
| 💊Capsule | ||||
| 50 mg | Oral | Mylan Pharmaceuticals Inc. × 2 listings | NDA | View NDC → |
| 150 mg | Oral | Mylan Pharmaceuticals Inc. × 2 listings | NDA | View NDC → |
| 💊Delayed-release capsule | ||||
| 25 mg | Oral | Horizon Therapeutics USA, Inc. × 3 listings | NDA | View NDC → |
| 75 mg | Oral | Horizon Therapeutics USA, Inc. × 3 listings | NDA | View NDC → |
| 💊Eye drops | ||||
| 6.5 mg/mL | Ophthalmic | Leadiant Biosciences, Inc. × 4 listings | NDA | View NDC → |
| 3.5 mg/mL | Ophthalmic | Recordati Rare Diseases, Inc. × 2 listings | NDA | View NDC → |
| 💊Oral powder | ||||
| 75 mg | Oral | Horizon Therapeutics USA, Inc. × 3 listings | NDA | View NDC → |
| 300 mg | Oral | Horizon Therapeutics USA, Inc. × 3 listings | NDA | View NDC → |
| 💊Bulk drug substance | ||||
| 1 kg/kg | — | Anonima Materie Sintetiche and Affini (AMSA) Spa × 2 listings | BULK INGREDIENT | View NDC → |
| 50 kg/50 kg | — | Azico Biophore India Private Limited | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Cambrex Profarmaco Milano Srl | BULK INGREDIENT | View NDC → |
| 1 g/g | — | Farmabios S.p.A. | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | HAS Healthcare Advanced Synthesis SA | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Honour Lab Limited | BULK INGREDIENT | View NDC → |
| 1 kg/kg | — | Maithri Laboratories Private Limited | BULK INGREDIENT | View NDC → |
Showing 30 of 30 products — FDA National Drug Code Directory. See every product, package size and price: browse all 30 Cysteamine NDCs →
📈 What people report — real-world data (FDA FAERS)
After a medicine reaches the market, patients, doctors and drugmakers can send the FDA reports of problems they think may be linked to it. Here’s what’s been reported for Cysteamine — a signal of what to watch for, not proof the drug caused it.
Source: openFDA, from the FDA Adverse Event Reporting System (FAERS). These are voluntary reports — they don’t prove the drug caused the effect, and counts reflect how often something was reported, not how often it actually happens. Reports also often name the very problem the medicine is taken for — a common reason to file one is that the drug didn’t help — so for a pain reliever you may see “pain” high on the list; that points to why the report was filed, not to the drug causing the symptom. This counts every report that lists Cysteamine in any role, so the total runs higher than the FDA’s official dashboard, which counts only cases where the drug is the suspect. For the authoritative figures, see the FDA FAERS Public Dashboard. Always talk to your pharmacist or doctor.
🏛️ The road to your pharmacy
How Cysteamine went from FDA review to the pharmacy shelf — the key milestones in its regulatory journey.
Source: Drugs@FDA.
🚨 Recall history
A recall is when a specific batch of a medicine is pulled from the market — usually a manufacturing issue, not a problem with the drug itself. Class I is most serious, Class III least.
Source: openFDA drug enforcement (recall) reports.
RxNorm Concept Web — From Ingredient to Every Form and Strength
This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.
RxCUI 3022 4 dose forms · 9 strengths
-
Dose form (SCDF) Delayed Release Oral Capsule RxCUI 1421466In current FDA listings -
Dose form (SCDF) Delayed Release Oral Granules RxCUI 2284509In current FDA listings -
Dose form (SCDF) Ophthalmic Solution RxCUI 393291In current FDA listings -
Dose form (SCDF) Oral Capsule RxCUI 371672In current FDA listings
Look up RxCUI 3022 in the RxCUI Atlas →
RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.
📦 Supply & shortage status
Whether Cysteamine is in short supply in the U.S. right now, plus any shortage history the FDA has on record. A shortage usually reflects a manufacturing or demand issue — not a safety problem with the drug.
Source: openFDA, from the FDA Drug Shortages database.
🏷️ Sold under these brand names
🏭 Manufacturers & labelers
RxNorm drug class
Cysteamine belongs to the Cystine Depleting Agent class.
Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.
🔬 Where this comes from
Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.
How we combine label and product data
HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 2 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.
For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Horizon Therapeutics USA, Inc. is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.
This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.