"Feb. 22, 2011 -- The FDA has issued a safety announcement notifying health care professionals that it has updated the pregnancy section of drug labels for the entire class of antipsychotic medications.
Antipsychotic drugs are used to "...
Clozaril Side Effects Center
Medical Editor: Melissa Conrad Stöppler, MD
Clozaril (clozapine) is an antipsychotic medication that is used to treat severe schizophrenia symptoms in people who have not responded to other medications. Clozapine is also used to help reduce the risk of suicidal behavior in people with schizophrenia or similar disorders. Side effects can include constipation, drooling, sleep disorders, increased sweating, or weight gain. Other side effects can occur. Clozaril is taken orally in tablet form, and an orally-disintegrating tablet that can be taken without water is available.
While you are taking clozapine, your blood may need to be tested every week for the first 6 months of treatment. It has been associated with agranulocytosis in some patients, a potentially fatal decrease in a certain type of white blood cells. Clozaril is not expected to be harmful to an unborn baby. Do not use clozapine without telling your doctor if you are pregnant or plan to become pregnant during treatment. Clozapine can pass into breast milk and may harm a nursing baby.
Our Clozaril Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.
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.
What is Patient Information in Detail?
Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.
Clozaril in Detail - Patient Information: Side Effects
Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Serious and sometimes fatal infections may occur during treatment with clozapine. Call your doctor right away if you have signs of infection such as:
- fever, chills, body aches, flu symptoms;
- mouth and throat ulcers;
- cough, sore throat;
- rapid heart rate; or
- rapid and shallow breathing.
Stop using clozapine and call your doctor at once if you have any of these serious side effects:
- seizure (black-out or convulsions);
- skin rash, bruising, severe tingling, numbness, pain, muscle weakness;
- fast or pounding heartbeats, chest pain, unusual tiredness, trouble breathing;
- feeling short of breath (even at night or with mild exertion), swelling in your hands or feet;
- feeling like you might pass out;
- slow heart rate, weak pulse, fainting, slow breathing (breathing may stop);
- high blood sugar (increased thirst, extreme hunger, fruity breath odor, increased urination, drowsiness);
- very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors;
- twitching or uncontrollable movements of your eyes, lips, tongue, face, arms, or legs; or
- nausea, vomiting, loss of appetite, and jaundice (yellowing of your skin or eyes).
Less serious side effects may include:
- dry mouth, blurred vision;
- drooling, especially at night;
- increased sweating;
- drowsiness, dizziness, spinning sensation; or
- sleep problems.
Read the entire detailed patient monograph for Clozaril (Clozapine) »
What is Patient Information Overview?
A concise overview of the drug for the patient or caregiver from First DataBank.
Clozaril Overview - Patient Information: Side Effects
To prevent constipation, maintain a diet adequate in fiber, drink plenty of water, and exercise. If you become constipated while using this drug, consult your pharmacist for help in selecting a laxative (e.g., stimulant-type with stool softener).
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
This medication may infrequently make your blood sugar level rise, which can cause or worsen diabetes. Rarely, very serious conditions such as diabetic coma may occur. Tell your doctor immediately if you develop symptoms of high blood sugar, such as increased thirst and urination. If you already have diabetes, be sure to check your blood sugars regularly. Your doctor may need to adjust your diabetes medication, exercise program, or diet.
This drug may also cause significant weight gain and a rise in your cholesterol (or triglyceride) levels. These effects, along with diabetes, may increase your risk for developing heart disease. Discuss the risks and benefits of treatment with your doctor.
Tell your doctor immediately if any of these unlikely but serious side effects occur: facial/muscle twitching, signs of infection (e.g., severe tiredness, fever, persistent sore throat), seizures, uncontrollable movements.
Seek immediate medical attention if any of these rare but very serious side effects occur: severe dizziness, fainting, mental/mood changes, difficulty breathing with exercise, swollen legs/feet, sudden weakness, pain/redness/swelling of the arms/legs, chest pain, persistent nausea/vomiting, stomach/abdominal pain, yellowing of eyes/skin.
This medication may rarely cause a very serious condition called neuroleptic malignant syndrome (NMS). Get medical help right away if you have any of the following symptoms: fever, muscle stiffness/pain/tenderness/weakness, severe tiredness, severe confusion, sweating, fast/irregular heartbeat, dark urine, change in the amount of urine.
A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.
Read the entire patient information overview for Clozaril (Clozapine)»
What is Prescribing information?
The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.
Clozaril FDA Prescribing Information: Side Effects
The following adverse reactions are discussed in more detail in other sections of the labeling:
- Agranulocytosis [see WARNINGS AND PRECAUTIONS].
- Orthostatic Hypotension, Bradycardia, and Syncope [see WARNINGS AND PRECAUTIONS].
- Seizures [see WARNINGS AND PRECAUTIONS].
- Myocarditis and Cardiomyopathy [see WARNINGS AND PRECAUTIONS].
- Increased Mortality in Elderly Patients with Dementia-Related Psychosis [see WARNINGS AND PRECAUTIONS].
- Eosinophilia [see WARNINGS AND PRECAUTIONS].
- QT Interval Prolongation [see WARNINGS AND PRECAUTIONS].
- Metabolic Changes (Hyperglycemia and Diabetes Mellitus, Dyslipidemia, and Weight Gain) [see WARNINGS AND PRECAUTIONS].
- Neuroleptic Malignant Syndrome [see WARNINGS AND PRECAUTIONS].
- Fever [see WARNINGS AND PRECAUTIONS].
- Pulmonary Embolism [see WARNINGS AND PRECAUTIONS].
- Anticholinergic Toxicity [see WARNINGS AND PRECAUTIONS].
- Interference with Cognitive and Motor Performance [see WARNINGS AND PRECAUTIONS].
- Tardive Dyskinesia [see WARNINGS AND PRECAUTIONS].
- Cerebrovascular Adverse Reactions [see WARNINGS AND PRECAUTIONS].
- Recurrence of Psychosis and Cholinergic Rebound after Abrupt Discontinuation [see WARNINGS AND PRECAUTIONS].
Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.
The most commonly reported adverse reactions ( ≥ 5%) across CLOZARIL clinical trials were: CNS reactions, including sedation, dizziness/vertigo, headache, and tremor; cardiovascular reactions, including tachycardia, hypotension, and syncope; autonomic nervous system reactions, including hypersalivation, sweating, dry mouth, and visual disturbances; gastrointestinal reactions, including constipation and nausea; and fever. Table 8 summarizes the most commonly reported adverse reactions ( ≥ 5%) in CLOZARIL-treated patients (compared to chlorpromazine-treated patients) in the pivotal, 6-week, controlled trial in treatment-resistant schizophrenia.
Table 8: Common Adverse Reactions ( ≥ 5%) in the
6-Week, Randomized, Chlorpromazine-controlled Trial in Treatment-Resistant
(N = 126)
(N = 142)
Table 9 summarizes the adverse reactions reported in CLOZARIL-treated patients at a frequency of 2% or greater across all CLOZARIL studies (excluding the 2-year InterSePT™ Study). These rates are not adjusted for duration of exposure.
Table 9: Adverse Reactions
( ≥ 2%) Reported in CLOZARIL-treated Patients (N=842) across all CLOZARIL
Studies (excluding the 2-year InterSePT™ Study)
|Body System Adverse Reaction*||CLOZARIL
N = 842
Percentage of Patients
|Central Nervous System|
|Autonomic Nervous System|
|†Rate based on population of approximately 1700 exposed during premarket clinical evaluation of CLOZARIL.|
Table 10 summarizes the most commonly reported adverse reactions ( ≥ 10% of the CLOZARIL or olanzapine group) in the InterSePT™ Study. This was an adequate and well-controlled, two-year study evaluating the efficacy of CLOZARIL relative to olanzapine in reducing the risk of suicidal behavior in patients with schizophrenia or schizoaffective disorder. The rates are not adjusted for duration of exposure.
Table 10: Incidence of Adverse Reactions in Patients
Treated with CLOZARIL or Olanzapine in the InterSePT™ Study ( ≥ 10%
in the CLOZARIL or olanzapine group)
N = 479
N = 477
|Dizziness (excluding vertigo)||27%||12%|
Class effect: Symptoms of dystonia, prolonged abnormal contractions of muscle groups, may occur in susceptible individuals during the first few days of treatment. Dystonic symptoms include: spasm of the neck muscles, sometimes progressing to tightness of the throat, swallowing difficulty, difficulty breathing, and/or protrusion of the tongue. While these symptoms can occur at low doses, they occur more frequently and with greater severity with high potency and at higher doses of first generation antipsychotic drugs. An elevated risk of acute dystonia is observed in males and younger age groups.
The following adverse reactions have been identified during post-approval use of clozapine. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Central Nervous System
Myasthenic syndrome and rhabdomyolysis.
Hemic and Lymphatic System
Read the entire FDA prescribing information for Clozaril (Clozapine) »
Additional Clozaril Information
Clozaril - User Reviews
Clozaril User Reviews
Now you can gain knowledge and insight about a drug treatment with Patient Discussions.
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
Get tips on therapy and treatment.