Clozaril (clozapine) is an atypical antipsychotic medication that works by affecting the activity of the brain’s neurotransmitters. This medication is only available by prescription. Due to the adverse side effects that may be experienced when taking this drug, you should carefully follow all the directions laid out by your doctor.

What Mental Health Conditions Does Clorazil Treat?

Clozaril is used to treat symptoms associated with severe schizophrenia, including hallucinations, breaks with reality, suicidal behavior, and extreme emotions, thoughts, or feelings. While Clozaril will help control behaviors that accompany the condition, it is not a “cure” for schizophrenia.

This drug is often prescribed to adults who need to augment other antipsychotic medications, or when they have not responded to other schizophrenia treatments. In most cases, Clozaril is suggested only after two or more alternative antipsychotic drugs have been tried.

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It may be helpful to consider pairing antipsychotic medication with some type of psychotherapy. Many available studies indicate that psychotropic medication treatment augmented with psychotherapy helps improve the quality of life to a greater degree for those in treatment than medication alone. Psychotherapy is a healthy way to address many emotions and behaviors associated with conditions Clozaril is used to treat.


Pay close attention to the dosage instructions provided by your doctor and/or pharmacist. Your clinician's directions will likely include the following recommendations:

  • Clozaril comes in a quick-dissolve tablet form and is usually taken one to three times per day. Take a consistent dose each day; do not alter the amount of medication you take without first speaking to your doctor. Up to two weeks may pass before you feel the full effect of this drug. It is important to continue taking the medication exactly as directed by your doctor, even after you begin to feel well.
  • If a dose is missed, take the missed dose as soon as you are able to. However, do not take the missed dose if you are close to the time for your next scheduled dose. Having too much of the drug in your system may cause an overdose. If you do not take the drug for two days or longer, speak to your doctor before you retake it.
  • If you overdose on Clozaril, call a poison helpline and seek emergency medical care right away. Signs and symptoms of overdose include sedation, fainting, problems with breathing, dizziness, delirium, erratic heartbeat, drooling, seizures, and coma. Overdoses above 2500 mg may be fatal; however some individuals have recovered from overdoses in excess of 4000 mg.

Important Information to Consider Before Using Clozaril

If you are allergic to clozapine, you should not take Clozaril. Common allergic reactions include the sudden appearance of hives and the swelling of the lips, face, tongue, or throat. Be sure to mention to your doctor if you have had any serious reactions to similar medications.

Clozaril is not recommended for use by older adults with dementia or dementia-related issues as it may increase the risk of death. If you have or have ever had heart disease, heart failure, irregular heartbeat, stroke, liver disease, kidney disease, diabetes, glaucoma or seizures, you should talk to your doctor before you take this drug. Tell your doctor if you have ever had urinary issues or problems with your prostate.
Let your doctor know if you have phenylketonuria. Orally disintegrating Clozaril tablets contain aspartame, which forms phenylalanine.

Clozaril may interact with other medications or supplements, including antihistamines, antidepressants, antibiotics, antifungal drugs, vitamins, minerals, herbal products, sleeping pills, HIV medications, high blood pressure medications, and more. If you are taking other prescription drugs or supplements, you should check with your doctor or pharmacist before taking this medication.

A single tablet of Clozaril may be extremely toxic to toddlers. Confusion, involuntary muscle movement, nerve damage, coma, and respiratory arrest may occur if toddlers ingest just 50-200 mg of clozapine.  

Information to Consider While Using Clozaril

When using this drug for treatment, consider the following:

  • Clozaril can cause serious heart and blood problems. Swelling of the heart (myocarditis) may lead to chest pain, difficulty breathing, and fatigue. Bone marrow issues may lead to a decrease in white blood cell count (agranulocytosis), making people undergoing treatment more prone to infection. Women, the elderly, and malnourished individuals are more susceptible to agranulocytosis. You will likely be given lab tests before you begin taking Clozaril and will need to continue to test regularly to be sure you are not being adversely affected by this medication. Testing will likely continue for at least four weeks after treatment.
  • If you are pregnant or become pregnant while taking this drug, you should talk to your doctor about alternative treatments for your condition. This medication can cause problems in newborns if taken during pregnancy or while breastfeeding.
  • This drug can make you extremely drowsy; using alcohol can worsen this side effect. Avoid driving, operating heavy machinery, swimming, and climbing while taking this drug.
  • Your surgeon or anesthesiologist needs to know that you are taking Clozaril if you plan to have any type of surgery, including oral surgery.
  • Smoking or using tobacco products can reduce the effectiveness of this medication.
  • Tell your doctor right away if you begin to experience signs of increased blood sugar or diabetes. This drug can cause a serious condition called ketoacidosis. If you experience loss of consciousness, extreme thirst, fruity-smelling breath, nausea, or vomiting, you should tell your doctor right away.

Possible Side Effects

People who are being treated with Clozaril may experience various side effects. Individuals who encounter serious side effects should seek emergency medical attention immediately. Serious side effects may include:

  • Confusion
  • Behavioral changes
  • Fever, sweating, or flu symptoms
  • Seizures
  • Muscle stiffness
  • Fever or sweating
  • Shaking hands that cannot be controlled
  • Vision changes
  • Sore throat
  • Bleeding or bruising
  • Difficulty with urination or loss of bladder control
  • Stomach upset, loss of appetite
  • Yellowed eyes or skin
  • Pain in the upper right portion of the stomach

Less serious side effects of this medication may include:

  • Drowsiness, dizziness, or tiredness
  • Restlessness
  • Dry mouth
  • Constipation
  • Headache
  • Increased saliva

How to Safely Withdraw from Clozaril

Although it is not classified as addictive, do not stop taking Clozaril abruptly. See your doctor before reducing or discontinuing this medication. Withdrawal symptoms may be significantly reduced by slowly tapering off of this drug. Possible symptoms of withdrawal include insomnia, delusions, hallucinations, or other psychotic symptoms.


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  5. Royal College of Psychiatrists. (2014). Antipsychotics. Retrieved from

Page content reviewed by James Pendleton, ND.