Cysteamine (Ophthalmic)

Cysteamine is an organic compound used to treat cystinosis, a genetic condition which affects the eye.


Cysteamine is a medication with a number of different indications, most notably the treatment of cystinosis, a genetic condition of the eye characterized by the accumulation of cystine, which is an amino acid. In addition to removing the build-up of cystine from cells in patients with cystinosis, it also promotes the transport of L-cysteine into cells which can be further utilized to create one of the most potent intracellular antioxidants, glutathione.

As a stable aminothiol, this organic compound contains both amine and thiol functional groups. In appearance, cysteamine is a white solid which can be dissolved in water, making it ideal for preparation as an intraocular eye drop.

This compound has been used therapeutically in the treatment of cystinosis since the 1950s, although it was not officially approved by the FDA until 1994. In 2013, an extended-release form of the medicine was approved. It is most notably marketed in the United States as Cystaran, Cystagon and Procysbi.

Type of medicine

  • Stable aminothiol

Conditions treated

  • Cystinosis

Side effects

Cysteamine can potentially cause some unwanted side effects, along with its desired effects. The most common side effects reported by patients undergoing treatment with Cysteamine include the following: diarrhea, drowsiness, loss of appetite, vomiting, nausea, fever, skin rash, abdominal pain.

As the patient continues the course of treatment with Cysteamine as prescribed, he or she should notice that most - if not all - side effects begin to lessen. If side effects appear to get worse or persist for a prolonged period, the patient is advised to contact their doctor as soon as possible. In some circumstances, a doctor, healthcare provider or pharmacist may be able to advise on ways to alleviate side effects which are causing discomfort, by recommending natural or over-the-counter remedies.

The majority of patients who undergo treatment with this medicine experience minimal side effects. Most doctors agree that the benefits of treating cystinosis outweigh the possibility of experiencing minor, temporary side effects as a result of Cysteamine therapy.

Other side effects experienced rarely, albeit often enough to warrant a mention, include the following: dizziness, mental depression, trembling, sore throat, confusion, dizziness, convulsions, increased thirst, breath odor, constipation, welts/hives, redness of the skin, weight loss and/or unusual weakness or tiredness.

The following side effects have also been reported, although their incidence is not known: double vision, bone lesions, chills, changes in color perception, coughing, eye pain, itching, hearing loss, pain in the legs, pain behind the eyes, irritated eyes, sores/ulcers/white spots on the lips and in the mouth, severe headaches, and/or reddish-purple lines on the arms/face/legs/trunk/groin. Patients who experience any of these side effects are advised to consult their doctor.

Because Cysteamine can affect the psychology of the patient in extremely rare cases, patients should be aware that they may experience confusion, mood swings, and memory issues. Caution should, therefore, be taken when administering this medicine to patients who already have a history of mental health issues.

Cysteamine can affect the vision and cause dizziness in some patients. Healthcare professionals, therefore, recommend that patients refrain from driving or operating heavy machinery directly after Cysteamine has been administered to avoid putting themselves or other road users at unnecessary risk.


Like all medicines, it is very important to take Cysteamine only as prescribed by a doctor. This means that patients must avoid taking more Cysteamine than they have been advised to, both in terms of frequency and dose size. In addition to this, patients must stop taking this medication if advised to do so by their doctor, even if they still have a supply of the drug remaining.

Cysteamine is administered intraocularly, in the form of eye drops. Patients should pay close attention to the instructions of their physician when this drug is prescribed so that they understand the dosage information correctly. Dose details should also be printed on the side of the packaging Cysteamine comes in. While the manufacturer may provide general dose instructions on the standard literature provided with Cysteamine, it should be reiterated that these guidelines can be altered on the judgement of the prescribing doctor, who will take various factors into account when determining the optimal dose (including the weight, height, age, and condition of the patient). Over time, a doctor may adjust the dose based on how the patient responds to treatment.

The recommended dose for patients with Cystinosis is one drop instilled in each eye, every waking hour of the day.

To correctly and effectively administer Cysteamine eye drops, patients should:

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  • Tilt back their head before pulling the lower lid of the eye downwards.
  • Hold the container of drops upside-down, as close to the eye as possible, while avoiding touching the eye.
  • Apply a small amount of pressure to the container - just enough to release a singular drop into the eye. Patients are advised to use no more than one drop per hour, as increased dosage will not alleviate the condition any further, but could potentially increase side effects.
  • Close the eye after the drop has been administered for approximately one minute while pressing gently on the area of the nose which meets the corner of the eye. This prevents drops from draining into the throat or nose area.
  • Repeat this process for the other eye.
  • Replace the cap on the container of Cysteamine drops, and return it to its storage area.

If a patient misses a dose, they should take the missed dose as soon as possible, before continuing with the standard dose schedule on an hourly basis from there onwards. However, some patients find it easier to wait until specific times (such as on-the-hour or on the half-hour) before administering a missed dose, in order to help them remember when the next dose is due.

Cystinosis is usually treated with a combination of different therapies which can include drugs, mineral and vitamin supplements. These medicines should only be used as directed by a doctor. Patients are advised to read all instructions and guides provided with all medicines, and should not change Cysteamine doses or schedules without the advice of a doctor.

Incidences of overdose concerning Cysteamine are rare. However, patients who experience symptoms of an overdose after using Cysteamine or any other medication are advised to contact their local poison control center immediately on 1800-222-1222 or the emergency services on 911.


All medications have the potential to interact with other chemicals or drugs within the human body. Sometimes, interactions can cause medicines to no longer be effective in treating the condition they were prescribed to alleviate. In other instances, interactions can result in potentially harmful side effects occurring.

For these reasons, it is imperative that patients keep a full and detailed list of all medicines they are currently undergoing treatment with. This includes multivitamin supplements, herbal remedies, over the counter products and complementary medicines, as well as prescribed medications.

There are currently no known drug interactions for Cysteamine, although this does not mean that no interactions exist. It simply means that there is inconclusive evidence to suggest any interactions exist because of a lack of published studies. Patients who feel they may have experienced an interaction should consult their doctor, and report their findings to the FDA if they feel it is pertinent.


Patients who are allergic to Cysteamine may also be allergic to penicillin and should inform their doctor of this and any other allergies prior to beginning treatment with this medicine. The presence of other medical conditions may also mean that Cysteamine is unsuitable for use in certain people. To ensure complete safety, patients should inform their doctor if they suffer from any of the following:

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  • Bone problems (including breaks or fractures)
  • Any form of skin rash
  • Stomach ulcers
  • Bleeding in the stomach or intestines
  • Depression
  • Drowsiness
  • Nervous system disorder

Alcohol should be avoided by patients undergoing treatment with Cysteamine. This is because potentially dangerous side effects can manifest when this medicine is combined with alcohol which can impair the thinking and reactions of the patient.

Cysteamine can be harmful if swallowed and can cause skin irritation if it comes into contact with the epidermis. Patients should, therefore, take great care to ensure that this medicine is correctly administered into the eye without spillages or inhalation.

Cysteamine should be used until a doctor advises otherwise. Patients should avoid sudden cessation of treatment, as this could potentially make cystinosis even worse.


Cysteamine should be stored at room temperature, away from sources of moisture, light, and heat. It is therefore unsuitable for storage in a bathroom, and should instead be kept in a locked medicine cabinet if possible, out of the reach of children and pets.

If the patient needs to dispose of unwanted, unused or expired Cysteamine, they should do so with care and attention, and in accordance with state law. Cysteamine should not be poured down a drain or toilet unless a qualified healthcare provider explicitly says so. Most pharmacies will be able to offer advice on how to dispose of unwanted medication, and many even offer "take-back"schemes where they will dispose of or recycle returned medicines.


Although Cysteamine is a greatly beneficial medication, it can potentially cause harm to patients when they fail to communicate effectively with their healthcare providers. As a treatment designed to treat the symptoms of cystinosis, Cysteamine prevents the accumulation of cystine in the eye cells of patients with the condition.

However, it also has a propensity to produce feelings of confusion, drowsiness, and depression in a small number of patients, and these side effects can affect the day-to-day functioning of the patient and give rise to potentially perilous situations unless the proper precautions are taken. Because of these risks, it is important for the patient to be upfront and open about their own medical history.

When used correctly, Cysteamine prevents cystine build-up and allows the patient to live a more fulfilling life. To achieve this, patient and doctor must work together to ascertain the most appropriate dose.