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Generic name: cysteaminesis-TEE-a-meen ]
Brand names: Cystagon, Procysbi
Drug class: Miscellaneous uncategorized agents

Medically reviewed by on Feb 22, 2024. Written by Cerner Multum.

What is Cystagon?

Cystagon works by reducing the amount of cystine (an amino acid) in the body.

Cystagon is used to treat nephropathic cystinosis (NEF-roe-PATH-ik SIS-tin-OH-sis), a rare genetic condition that causes a build-up of cystine in the kidneys and other organs. Too much cystine can cause kidney failure or other medical problems.

Cystagon is for use in adults and children, but Procysbi should not be given to a child younger than 1 year old.

Cystagon may also be used for purposes not listed in this medication guide.

Cystagon side effects

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 Cystagon):

Common side effects of Cystagon may include:

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.


Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use Cystagon if you are allergic to Cystagon or penicillamine.

Tell your doctor if you have ever had:

It is not known whether this medicine will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

You should not breastfeed while using this medicine.

How should I use Cystagon?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Swallow the capsule whole and do not crush or chew it.

If you cannot swallow a capsule whole, carefully follow the patient instructions for opening the capsule and mixing the medicine with certain foods. Your doctor may recommend that you use Cystagon oral granules.

Do not crush or chew oral granules.

Procysbi works best if you take it without food, at least 30 minutes before or 2 hours after a meal. If you cannot take the medicine without eating, eat only a small amount (1/2 cup) of food within 1 hour before or 1 hour after you take the medicine.

Whether you take the medicine with or without food, take it the same way each time.

To mix the oral granules or medicine from a capsule with food:

Procysbi also comes with instructions for giving the mixture through a gastronomy tube (14 French or larger).

Cystagon doses are based on weight (especially in children and teenagers). Your dose needs may change if you gain or lose weight.

You will need frequent medical tests.

You should not stop using Cystagon without your doctor's advice. Stopping suddenly may make your condition worse.

Cystinosis is often treated with a combination of drugs, including vitamin and mineral supplements. Use all medications as directed and read all medication guides you receive. Do not change your dose or dosing schedule without your doctor's advice.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the missed dose as soon as you remember.

Do not use two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Cystagon?

Avoid driving or hazardous activity until you know how Cystagon will affect you. Your reactions could be impaired.

Avoid drinking alcohol while taking Procysbi. Alcohol can make the medicine less effective or cause side effects.

What other drugs will affect Cystagon?

Take Procysbi at least 1 hour before or 1 hour after taking any medicine that contains bicarbonate or carbonate.

Other drugs may affect Cystagon, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.