Side Effects

The health care prescriber will decide on the best treatment, and will consider factors including symptoms experienced, current medical conditions, medications already being taken, and potential side effects that a new medication might cause.

Side effects vary from person to person and are not always the same for everyone.

People taking CLOZARIL might experience one or more of the following side effects:


Please see additional Important Safety Information below.

  • The most serious side effect associated with CLOZARIL is called agranulocytosis. This occurs when your white blood cell count is significantly lowered and your body’s immune system becomes highly vulnerable to infection. For this reason, people taking CLOZARIL are required to have regular monitoring while being treated.

In addition to agranulocytosis (the most serious side effect associated with CLOZARIL), the following side effects have been reported:

  • Seizures or convulsions: The higher the dosage, the greater the risk of seizures. Also, people who have had seizures in the past are more likely to have them with CLOZARIL.
    If a person suffers a seizure, he or she should tell their health care prescriber at once.
  • Fast or irregular heartbeat: If this happens, the dosage may be reduced, or this side effect may be treated with another medication.
  • Myocarditis (an inflammation of a muscle in the heart): The risk is greatest during the first month of CLOZARIL therapy.
  • Orthostatic hypotension (a fall in blood pressure when suddenly standing up); the risk is highest when treatment with CLOZARIL is started.
  • CLOZARIL is not approved for use in patients with dementia-related psychosis. Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death.
  • Common side effects include drowsiness, dizziness, headache, tremor, fast heart rate, low blood pressure, fainting, drooling, sweating, dry mouth, visual disturbances, constipation, nausea, and fever.
  • Speak with a health care prescriber if you have a history of clozapine-induced agranulocytosis, severe granulocytopenia, or sensitivity to clozapine.

Please see Important Safety Information