Health Library

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, 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.
• Oral suspension: Shake for 10 seconds before each use. Measure the dose with the dosing syringe that comes with the package.
• Drink plenty of liquids to help avoid constipation.
• 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 miss your dose 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. Oral suspension: Do not refrigerate or freeze. Throw away any unused medicine 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.

• Do not use this medicine together with benztropine, cyclobenzaprine, or diphenhydramine.
• Some medicines can affect how clozapine works. Tell your doctor if you are using any of the following:
  • Bupropion, carbamazepine, cimetidine, dolasetron, duloxetine, enoxacin, escitalopram, fluoxetine, fluvoxamine, levomethadyl acetate, lithium, mefloquine, methadone, paroxetine, pentamidine, phenytoin, rifampin, sertraline, St John's wort, tacrolimus, terbinafine
  • Birth control pills
  • Blood pressure medicine
  • Diuretic (water pill)
  • Medicine for heart rhythm problems (including amiodarone, encainide, flecainide, procainamide, propafenone, quinidine, sotalol)
  • Medicine to treat an infection (including ciprofloxacin, erythromycin, gatifloxacin, moxifloxacin, sparfloxacin)
  • Other medicine to treat mental health problems (including chlorpromazine, droperidol, iloperidone, pimozide, thioridazine, ziprasidone)
  .
• Do not drink alcohol while you are using this medicine.
• Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.

Warnings While Using This Medicine:

• Tell your doctor if you are pregnant, or if you have kidney disease, liver disease, dementia, diabetes, digestion problems, glaucoma, heart or blood vessel disease, heart failure, heart rhythm problems, high cholesterol, enlarged prostate, stomach or bowel problems, or a history of head injury, heart attack, stroke, seizures, or alcohol addiction. Tell your doctor if you smoke or drink products that contain caffeine. Tell your doctor if you have phenylketonuria.
• Do not breastfeed while you are using this medicine.
• This medicine may cause the following problems:
  • Heart problems or changes in heart rhythm
  • Stomach or bowel problems, including severe constipation
  • Serious skin reaction, including drug reaction with eosinophilia and systemic symptoms
  • Changes in blood sugar levels
  • Neuroleptic malignant syndrome, which can be life-threatening
  • Liver problems
  • Increased risk of blood clots, including heart attack or stroke
  • Anticholinergic effects, when used with other medicines
  • Tardive dyskinesia (a movement disorder)
• This medicine lowers the number of white blood cells. This weakens your immune system, so you may get infections more easily. Wash your hands often. Avoid people who are sick.
• This medicine can make you dizzy, drowsy, lightheaded, or to have trouble with thinking or controlling body movements, which may lead to falls, fractures or other injuries. Do not drive 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.
• Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.
• 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, red skin rash
• Blurred vision, confusion, trouble passing urine, eye pain, flushing or redness of the face, dry eyes, mouth, nose, or throat
• Chest pain, trouble breathing, numbness or weakness on one side of your body, lower leg pain, problems with vision, speech, or walking
• Dark urine or pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes
• Fast, slow, pounding, or uneven heartbeat
• Fever, chills, cough, sore throat, body aches
• Increased thirst or hunger
• Jerky muscle movement that you cannot control, often in your face, tongue, or jaw
• Lightheadedness, dizziness, fainting
• Seizures
• Severe constipation
• Sweating, muscle stiffness
• Unusual bleeding, bruising, or weakness

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

• Excess saliva or drooling
• Unusual drowsiness or sleepiness, headache
• 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

Last Updated: 9/6/2024