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

There may be other brand names for this medicine.

When This Medicine Should Not Be Used

You should not use this medicine if you have had an allergic reaction to clozapine. Do not use this medicine if you have taken clozapine before and it caused severe blood problems. You should not use this medicine if you have a bone marrow disorder, uncontrolled epilepsy, or a bowel blockage. This medicine should not be given to a person who is in a coma or has similar nervous system problems. Do not breastfeed while you are using this medicine.

How to Use This Medicine

Tablet, Dissolving Tablet

  • Your doctor will tell you how much of this medicine to use and how often. Your dose may need to be changed several times in order to find out what works best for you. Do not use more medicine or use it more often than your doctor tells you to.
  • Drink plenty of fluids to help avoid constipation.
  • If you are using the disintegrating tablet, make sure your hands are dry before you handle the tablet. Do not open the blister pack that contains the tablet until you are ready to take it. Remove the tablet from the blister pack by peeling back the foil, then taking the tablet out. Do not push the tablet through the foil. Place the tablet in your mouth. It should melt quickly. After the tablet has melted, swallow or take a drink of water. The disintegrating tablet may also be chewed.

If a dose is missed:

  • If you miss a dose or forget to use your medicine, use it as soon as you can. If it is almost time for your next dose, wait until then to use the medicine and skip the missed dose. Do not use extra medicine to make up for a missed dose.
  • If for any reason you stop taking clozapine for longer than 2 days, do not start back on the same dose. Ask your doctor how much you should take.

How to Store and Dispose of This Medicine

  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.
  • Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
  • Keep all medicine away from children and never share your medicine with anyone.

Drugs and Foods to Avoid

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

  • There are many other drugs that can interact with clozapine. Make sure your doctor knows about all other medicines you are using.
  • Make sure your doctor knows if you are using carbamazepine (Tegretol®), cimetidine (Tagamet®), ciprofloxacin (Cipro®), phenytoin (Dilantin®), rifampin (Rifadin®, Rimactane®), or medicine to treat depression (such as citalopram, fluoxetine, fluvoxamine, paroxetine, sertraline, venlafaxine, Celexa®, Effexor®, Luvox®, Paxil®, Prozac®, or Zoloft®).
  • Make sure your doctor knows if you are also using a diuretic or "water pill" (such as furosemide or hydrochlorothiazide [HCTZ]), medicine to lower blood pressure, or medicine for heart rhythm problems (such as amiodarone, disopyramide, dofetilide, encainide, flecainide, procainamide, propafenone, quinidine, sotalol, Betapace®, Cordarone®, Norpace®, Rythmol®, Tambocor®, or Tikosyn®). Tell your doctor if you are using atropine, dicyclomine (Bentyl®), glycopyrrolate (Robinul®), propantheline (Pro-Banthine®), or scopolamine.
  • Tell your doctor if you are also using methadone (Dolophine®), pentamidine (Pentam®), tacrolimus (Prograf®), certain antibiotics (such as erythromycin, gatifloxacin, moxifloxacin, sparfloxacin, Avelox®, or Zagam®), medicine to treat malaria (such as mefloquine or Lariam®), medicine to treat mental illness (such as chlorpromazine, droperidol, haloperidol, iloperidone, mesoridazine, pimozide, risperidone, thioridazine, ziprasidone, Geodon®, Haldol®, Inapsine®, Mellaril®, Orap®, Risperdal®, Serentil®, or Thorazine®), medicine to treat anxiety (such as alprazolam, clonazepam, diazepam, Valium®, or Xanax®), or medicine for nausea or vomiting (such as prochlorperazine, promethazine, Compazine®, or Phenergan®).
  • Tell your doctor if you are using any medicines that make you sleepy. These include sleeping pills, cold and allergy medicine, narcotic pain relievers, and sedatives.
  • Tell your doctor if you smoke tobacco or drink caffeine-containing products. Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or if you have had neuroleptic malignant syndrome (NMS). Tell your doctor if you have kidney disease, liver disease (including hepatitis), low levels of potassium or magnesium in your blood, lung disease, an enlarged prostate, or digestion problems such as constipation. Tell your doctor if you have glaucoma, if you have ever had a head injury, or if you have a history of seizures or stroke.
  • Contact your doctor right away if you have any changes to your heart rhythm. Some possible symptoms are dizziness, fainting, or a fast, pounding, or uneven heartbeat. Make sure your doctor knows if you have ever had a heart rhythm problem such as QT prolongation, or if you have other heart or circulation problems, such as a recent heart attack, heart failure, low blood pressure, blood clots, or a stroke. Tell your doctor if there is a history of heart disease in your family.
  • Call your doctor right away if you have flu-like symptoms, sores in your mouth, sore throat, unusual tiredness or weakness, or fever. These might be symptoms of agranulocytosis, a serious problem with the blood. You might get infections more easily. Avoid people who are sick or have infections. Wash your hands often.
  • This medicine can cause drowsiness or seizures. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert. Stand or sit up slowly if you feel lightheaded or dizzy.
  • Stop using this medicine and contact your doctor as soon as possible if you have chest pain or discomfort, a fast heartbeat, trouble breathing, fever, or unusual tiredness or weakness. These can be symptoms of myocarditis, which is a serious problem with your heart.
  • This medicine is approved only for patients who have schizophrenia or schizoaffective disorder. This medicine is not approved for use in older people who have dementia, because it can increase the risk of death. This risk has not been shown for the approved uses of this medicine.
  • Check with your doctor right away if you have fever, sweating, unusual confusion, uneven heartbeat, or changes in blood pressure. These could be symptoms of neuroleptic malignant syndrome (NMS).
  • Check with your doctor right away if you have jerky muscle movements that you cannot control. These movements may happen in your face, tongue, jaw, or other muscles. These are symptoms of tardive dyskinesia. This problem may not go away after you stop using the medicine.
  • Your doctor will need to check your blood at regular visits while you are using this medicine. Be sure to keep all appointments. You will not be given more medicine if you do not have these tests. You might need to continue the blood tests even after you stop medicine.
  • Tell your doctor if you have diabetes, because this medicine may raise your blood sugar.
  • Tell your doctor if you have phenylketonuria. The orally disintegrating tablet contains phenylalanine, which can make this condition worse.
  • Make sure any doctor or dentist who treats you knows that you are using this medicine. You may need to stop using this medicine several days before having surgery or medical tests.

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
  • Chills, cough, body aches
  • Dark-colored urine or pale stools
  • Fast or pounding heartbeat with tiredness, chest pain, fever, or trouble breathing
  • Fast, pounding, or uneven heartbeat
  • Fever
  • Increased thirst or hunger
  • Jerky muscle movement that you cannot control, often in your face, tongue, or jaw
  • Lightheadedness, dizziness, or fainting
  • Muscle spasms in your neck or tongue, trouble swallowing, trouble breathing
  • Nausea, vomiting, loss of appetite, or pain in your upper stomach
  • 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
  • Trouble breathing, especially at night or with exercise
  • Unusual tiredness or weakness
  • Yellowing of your skin or the whites of your eyes

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

  • Constipation
  • Dry mouth, blurred vision or vision problems
  • Excess saliva or drooling
  • Headache
  • Increased sweating
  • Sleepiness
  • 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 06/12/2013

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This page was last updated: June 18, 2013

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