Clozapine (By mouth)


Clozapine (KLOE-za-peen)

Treats schizophrenia. Also lowers the risk of suicidal behavior in patients who have schizophrenia or schizoaffective disorder.

Brand Name(s)

Clozaril, FazaClo, Versacloz

When This Medicine Should Not Be Used

How to Use This Medicine

Liquid, Tablet, Dissolving Tablet

  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you.
  • Make sure your hands are dry before you handle the disintegrating tablet. Peel back the foil from the blister pack, then remove the tablet. Do not push the tablet through the foil. Place the tablet in your mouth. After it has melted, swallow or take a drink of water. The disintegrating tablet may also be chewed.
  • Shake the bottle of oral liquid for 10 seconds before each use. Measure the dose with the dosing syringe that comes with the package. Wash the oral syringe with warm water after using it.
  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Call you doctor if you stop taking clozapine for longer than 2 days. Your dose may need to be changed.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Do not refrigerate or freeze the oral liquid.
  • Throw away any unused oral liquid 100 days after you open the bottle for the first time.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Some medicines can affect how clozapine works. Tell your doctor if you also use carbamazepine, cimetidine, ciprofloxacin, dolasetron, enoxacin, erythromycin, gatifloxacin, halofantrine, levomethadyl acetate, lithium, mefloquine, methadone, moxifloxacin, pentamidine, phenytoin, probucol, rifampin, St John's wort, sparfloxacin, tacrolimus, or terbinafine.
  • Make sure your doctor knows if you also use birth controls pills, a diuretic (water pill), medicine for heart rhythm problems, medicine to lower blood pressure, or medicine to treat depression, anxiety, or mental illness.
  • Tell your doctor if you drink alcohol or if you are using any medicine that makes you sleepy, such as allergy medicine or narcotic pain medicine.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, diabetes, phenylketonuria, low levels of potassium or magnesium in your blood, heart rhythm problems, heart failure, low blood pressure, an enlarged prostate, or digestion problems. Tell your doctor if you have glaucoma, if you have ever had a head injury, or if you have a history of seizures, heart attack, stroke, or alcohol abuse. Tell your doctor if you smoke or drink alcohol or products that contain caffeine.
  • This medicine may cause the following problems:
    • Low white blood cell count (can increase risk of infection)
    • Myocarditis or cardiomyopathy
    • Heart rhythm problems or low blood pressure
    • Changes in blood sugar levels
    • Neuroleptic malignant syndrome
    • Seizures
  • This medicine can make you dizzy, drowsy, or lightheaded. Do not drive, use machines, or do anything else that could be dangerous until you know how this medicine affects you. Stand or sit up slowly if you feel lightheaded or dizzy.
  • Drink plenty of liquids to help avoid constipation.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments. You may need to continue to have blood tests even after you stop taking this medicine.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Blistering, peeling, or red skin rash
  • Chest pain, trouble breathing
  • Chills, cough, fever, body aches
  • Dark urine or pale stools, nausea, vomiting, loss of appetite, pain in your upper stomach, yellow skin or eyes
  • Difficult or painful urination
  • Fast, pounding, or uneven heartbeat
  • Increased thirst or hunger
  • Jerky muscle movement that you cannot control, often in your face, tongue, or jaw
  • Lightheadedness, dizziness, or fainting
  • Pain in your lower leg (calf)
  • Seizures
  • Sores in your mouth or sore throat
  • Sweating, confusion, muscle stiffness
  • Swelling in your hands, ankles, or feet
  • Unusual bleeding or bruising
  • Unusual tiredness or weakness

If you notice these less serious side effects, talk with your doctor:

  • Constipation, upset stomach
  • Excess saliva or drooling
  • Sleepiness or trouble sleeping
  • Weight gain

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Version Info

  • Last reviewed on 8/4/2014

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission ( URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- 2013 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.