This information from Lexicomp® explains what you need to know about this medication, including what it’s used for, how to take it, its side effects, and when to call your healthcare provider.
Brand Names: US
Clozaril; Versacloz
Brand Names: Canada
AA-Clozapine; Clozaril; GEN-Clozapine
- This drug may lower the ability of your bone marrow to make white blood cells. This can lead to very bad and sometimes deadly infections. You will need to have your blood work checked before, during, and after treatment is stopped. Do what the doctor tells you about blood tests while taking this drug.
- This drug may cause seizures in some people. The chance of seizures may be higher with higher doses or if you have ever had seizures. The chance may also be higher if you take other drugs that may raise the risk of seizures, if you have a health problem that raises your risk of seizures, or in some patients who drink alcohol. Use care when driving and doing other tasks or actions (like climbing and swimming) that may not be safe for you or others if you pass out.
- This drug may raise the chance of a very bad and sometimes deadly heart problem (myocarditis). Most of the time, these heart problems have happened within the first 2 months of care but may happen at anytime. Call your doctor right away if you have a big weight gain, an abnormal heartbeat, chest pain or pressure, fast heartbeat, fever, flu-like signs, shortness of breath, swelling in the arms or legs, or severe dizziness or passing out.
- Low blood pressure, passing out, slow heartbeat, and other severe heart problems have happened with this drug. These problems can be deadly. The chance of these problems is highest when this drug is first started. It may also be higher if the drug is stopped and restarted. Do not take more than you were told or raise your dose faster than you were told. Tell your doctor if you have heart or blood vessel problems, including problems with blood vessels in your brain. Tell your doctor if you are dehydrated, have lots of fluid loss, or if you take drugs for high blood pressure.
- There is a higher chance of death in older adults who take this drug for mental problems caused by dementia. Most of the deaths were linked to heart disease or infection. This drug is not approved to treat mental problems caused by dementia.
What is this drug used for?
- It is used to treat schizophrenia.
- It is used to treat problems with how one acts.
- It may be given to you for other reasons. Talk with the doctor.
What do I need to tell my doctor BEFORE I take this drug?
- If you are allergic to this drug; any part of this drug; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
- If you have a low white blood cell count.
- If you have bone marrow disease.
- If you have any of these health problems: Low potassium or magnesium levels.
- If you have ever had a low white blood cell count when taking a drug before.
- If you are taking any drugs that can stop your bone marrow from making some of the cells that your body needs. There are many drugs that can do this. Ask your doctor or pharmacist if you are not sure.
- If you are not able to get blood tests as you have been told by your doctor.
This is not a list of all drugs or health problems that interact with this drug.
Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.
What are some things I need to know or do while I take this drug?
- Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
- Avoid driving and doing other tasks or actions that call for you to be alert until you see how this drug affects you.
- To lower the chance of feeling dizzy or passing out, rise slowly if you have been sitting or lying down. Be careful going up and down stairs.
- Have your blood work and heart function checked as you have been told by your doctor.
- If you have phenylketonuria (PKU), talk with your doctor. Some products have phenylalanine.
- High blood sugar or diabetes, high cholesterol, and weight gain have happened with drugs like this one. These may raise the chance of heart and brain blood vessel disease.
- If you have high blood sugar (diabetes), you will need to watch your blood sugar closely.
- Do not stop taking this drug all of a sudden without calling your doctor. You may have a greater risk of signs of withdrawal. If you need to stop this drug, you will want to slowly stop it as ordered by your doctor.
- If you start or stop smoking, talk with your doctor. How much drug you take may need to be changed.
- Tell your doctor if you use caffeine products (for example, tea, coffee, cola) and chocolate. How much of this drug you take may need to be changed.
- Talk with your doctor before you use alcohol, marijuana or other forms of cannabis, or prescription or OTC drugs that may slow your actions.
- Be careful in hot weather or while being active. Drink lots of fluids to stop fluid loss.
- Dizziness, sleepiness, and feeling less stable may happen with this drug. These may lead to falling, which can cause broken bones or other health problems.
- An unsafe heartbeat that is not normal (long QT on ECG) has happened with this drug. Chest pain, heart attack, and sudden deaths have also rarely happened in people taking this drug. Talk with the doctor.
- Blood clots have happened with this drug. Tell your doctor if you have ever had a blood clot. Talk with your doctor.
- This drug can cause very bad stomach or bowel problems like very bad constipation or bowel block. Sometimes, this has been deadly. To help avoid these problems, drink lots of noncaffeine liquids unless told to drink less liquid by your doctor. Laxatives may also help. Talk with your doctor.
- Older adults with dementia taking drugs like this one have had a higher number of strokes. Sometimes these have been deadly. This drug is not approved to treat mental problems caused by dementia.
- If you are 60 or older, use this drug with care. You could have more side effects.
- Tell your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding. You will need to talk about the benefits and risks to you and the baby.
- Taking this drug in the third trimester of pregnancy may lead to side effects or withdrawal in the newborn.
- If you are breast-feeding, the doctor will need to watch your baby for certain side effects.
What are some side effects that I need to call my doctor about right away?
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Signs of infection like fever, chills, very bad sore throat, ear or sinus pain, cough, more sputum or change in color of sputum, pain with passing urine, mouth sores, or wound that will not heal.
- Signs of high blood sugar like confusion, feeling sleepy, unusual thirst or hunger, passing urine more often, flushing, fast breathing, or breath that smells like fruit.
- Signs of high or low blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
- Shakiness, trouble moving around, or stiffness.
- Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
- Seizures.
- Feeling very tired or weak.
- Change in eyesight.
- Passing urine more often.
- Hard or dry stools; bowel movements that are not as often as normal; severe constipation; stomach pain, bloating, or swelling; trouble passing gas; or upset stomach or throwing up.
- Call your doctor right away if you have signs of a blood clot like chest pain or pressure; coughing up blood; shortness of breath; swelling, warmth, numbness, change of color, or pain in a leg or arm; or trouble speaking or swallowing.
- Liver problems have happened with this drug. Sometimes, these have been deadly. Call your doctor right away if you have signs of liver problems like dark urine, tiredness, decreased appetite, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
- A very bad and sometimes deadly health problem called neuroleptic malignant syndrome (NMS) may happen. Call your doctor right away if you have any fever, muscle cramps or stiffness, dizziness, very bad headache, confusion, change in thinking, fast heartbeat, heartbeat that does not feel normal, or are sweating a lot.
- Some people may get a severe muscle problem called tardive dyskinesia. This problem may lessen or go away after stopping this drug, but it may not go away. The risk is greater with diabetes and in older adults, especially older females. The risk is greater with longer use or higher doses, but it may also occur after short-term use with low doses. Call your doctor right away if you have trouble controlling body movements or problems with your tongue, face, mouth, or jaw like tongue sticking out, puffing cheeks, mouth puckering, or chewing.
What are some other side effects of this drug?
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
- Dizziness or headache.
- Feeling sleepy.
- Constipation.
- Dry mouth.
- Upset stomach or throwing up.
- Heartburn.
- Weight gain.
- Trouble sleeping.
- More saliva.
- Sweating a lot.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to your national health agency.
You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.
How is this drug best taken?
Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.
All products:
- Take with or without food.
- Keep taking this drug as you have been told by your doctor or other health care provider, even if you feel well.
Oral-disintegrating tablet:
- Do not push the tablet out of the foil when opening. Use dry hands to take it from the foil. Place on your tongue and let it dissolve. Water is not needed. Do not swallow it whole. You may chew the tablet.
Liquid (suspension):
- Shake well before use.
- Measure liquid doses carefully. Use the measuring device that comes with this drug.
- Do not draw into a syringe and store for future use.
What do I do if I miss a dose?
- Take a missed dose as soon as you think about it.
- If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
- Do not take 2 doses at the same time or extra doses.
- If you miss 1 day or more of this drug, you may need to restart at a lower dose to lower the risk of side effects. Call your doctor to find out how to restart.
How do I store and/or throw out this drug?
All products:
- Store at room temperature. Do not refrigerate or freeze.
- Store in a dry place. Do not store in a bathroom.
- Protect from light.
- Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
- Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.
Oral-disintegrating tablet:
- Store in pouch until ready for use.
- Use oral-disintegrating tablet right after opening. Throw away any part of opened pouch that is not used.
Liquid (suspension):
- Throw away any part not used 100 days after opening the first time.
General drug facts
- If your symptoms or health problems do not get better or if they become worse, call your doctor.
- Do not share your drugs with others and do not take anyone else’s drugs.
- Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
- Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
- If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.
Consumer Information Use and Disclaimer
This generalized information is a limited summary of diagnosis, treatment, and/or medication information. It is not meant to be comprehensive and should be used as a tool to help the user understand and/or assess potential diagnostic and treatment options. It does NOT include all information about conditions, treatments, medications, side effects, or risks that may apply to a specific patient. It is not intended to be medical advice or a substitute for the medical advice, diagnosis, or treatment of a health care provider based on the health care provider’s examination and assessment of a patient’s specific and unique circumstances. Patients must speak with a health care provider for complete information about their health, medical questions, and treatment options, including any risks or benefits regarding use of medications. This information does not endorse any treatments or medications as safe, effective, or approved for treating a specific patient. UpToDate, Inc. and its affiliates disclaim any warranty or liability relating to this information or the use thereof. The use of this information is governed by the Terms of Use, available at https://www.wolterskluwer.com/en/know/clinical-effectiveness-terms.
Last Reviewed Date
2024-10-25
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