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Clozapine

Brand names: Clozaril, Versacloz

Clozapine is the most effective medicine for schizophrenia that hasn't responded to others. It needs regular blood tests.

Brand namesClozaril, Versacloz
Type of medicineAntipsychotic
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It also lowers suicide risk in schizophrenia. Pharmacies dispense it only with up-to-date blood counts.

What it's used for

  • Treatment-resistant schizophrenia
  • Lowering suicidal behavior in schizophrenia

How to take it

  • Take it as prescribed and keep every blood test.
  • If you miss more than 2 days, call your provider; you need to restart at a low dose.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Sleepiness
  • Drooling
  • Constipation
  • Weight gain
  • Fast heartbeat
Call 911Fever, sore throat, or other signs of infection (possible very low white blood cells)
Call 911Seizure
Call 911Chest pain, fast heartbeat, or shortness of breath (heart inflammation)
Call your provider todayNo bowel movement for several days or belly pain (severe constipation can be life-threatening)

Warnings

  • Boxed warnings: severe low white blood cells, low blood pressure and fainting, seizures, heart inflammation, and higher death risk in older adults with dementia.

Other medicines, foods, and alcohol

  • Smoking lowers its level; quitting can raise it sharply.
  • Fluvoxamine and ciprofloxacin raise its level a lot.
  • Carbamazepine must not be taken with it.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Talk with your provider.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.