Clozapine, Clozapine Odt

Introduction

Written by Lee Holland, PharmD, MPH
Medically reviewed by Victor Nguyen, PharmD, MBA
Updated on October 3, 2023

Clozapine (KLOE za peen) is a generic medication prescribed for schizophrenia and suicidal behavior in certain people. Clozapine belongs to a group of drugs called atypical antipsychotics.

This article doesn’t provide coupons for all forms of clozapine. To find coupons for clozapine oral disintegrating tablet, see this article.

Boxed warnings

Clozapine has boxed warnings, which are the most serious warnings from the Food and Drug Administration (FDA). These include:

• risk of severe, low neutrophil levels (a type of white blood cell)
• risk of serious low blood pressure, slow heart rate, and fainting
• risk of seizures
• risk of serious conditions of the heart muscle
• increased risk of death in older adults with dementia-related psychosis

For details, see the “Interactions and warnings for clozapine” section.

Side effects of clozapine

Clozapine may cause mild or serious side effects. More common mild side effects of clozapine and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about clozapine’s side effects, ask your doctor or pharmacist. You can also refer to the prescribing information for clozapine listed in the “Resources” section.

Mild side effects

More common mild side effects reported with some forms of clozapine are listed below. These side effects may differ based on the form of clozapine you take.

This article doesn’t include all possible mild side effects of the drug. To learn more about clozapine’s side effects based on the form, refer to the prescribing information for clozapine listed in the “Resources” section.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Clozapine oral tablet and oral disintegrating tablet’s mild side effects include:

• sleepiness
• dizziness
• headache
• fast heartbeat
• mild allergic reaction*

* For details about this side effect, see the “Interactions and warnings for clozapine” section.

Serious side effects

Serious side effects of clozapine are listed below.

This article doesn’t include all possible serious side effects of the drug. To learn more about clozapine’s side effects based on the form, refer to the prescribing information for clozapine listed in the “Resources” section.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, clozapine’s serious side effects include:

• severe constipation or intestinal blockage
• eosinophilia (too many of certain type of white blood cells)
• long QT syndrome (problem with the electrical activity of the heart)
• metabolism changes, including diabetes, high blood sugar, high cholesterol, and weight gain
• neuroleptic malignant syndrome (NMS), which is a life threatening reaction that causes a fast heartbeat, high fever, and stiff muscles
• liver damage
• fever
• blood clots in the lungs
• problems with thinking and coordination
• tardive dyskinesia (uncontrolled twitching or movements)
• serious skin reaction called Stevens-Johnson syndrome, which may be life threatening
• boxed warning: risk of risk of severe low neutrophil levels (a type of white blood cell)
• boxed warning: serious low blood pressure
• boxed warning: slow heart rate, fainting, and seizures
• boxed warning: serious conditions of the heart muscle
• boxed warning: increased risk of death in older adults with dementia-related psychosis
• severe allergic reaction*

* For details about this side effect, see the “Interactions and warnings for clozapine” section.

Common questions about clozapine

Below you’ll find answers to a few commonly asked questions about clozapine.

What is clozapine’s mechanism of action? How does the drug work? 

Scientists think that clozapine works by controlling the levels of certain natural chemicals in the brain, such as dopamine and serotonin. This is the mechanism of action (how the drug works) of clozapine.

It can take up to 6 weeks before clozapine begins working.

If you’d like to know more about how clozapine works, talk with your doctor or pharmacist.

Can clozapine be used for anxiety?

No, clozapine can’t be used for anxiety. Clozapine is used to treat severe schizophrenia and suicidal behavior.

If you have questions about treatment options for anxiety, talk with your doctor.

What brand names are available for clozapine?

The brand name for generic clozapine tablet is Clozaril.

A generic medication is an identical copy of the active drug in a brand-name medication. (An active drug is the ingredient that makes a medication work.) Generic drugs are believed to be as effective and safe as brand-name drugs. And generic drugs typically cost less compared to brand-name drugs.

If you’d like more information about generic versus brand-name drugs, talk with your doctor or pharmacist.

Is clozapine similar to clonazepam?

No, they’re not. Although they sound the same, clozapine is not similar to clonazepam.

Clozapine is an atypical antipsychotic used to treat schizophrenia and suicidal behavior in certain people. Clonazepam is a benzodiazepine used to treat specific seizure disorders and panic disorder.

If you would like to know more about the differences between clozapine and clonazepam, ask your doctor or pharmacists.

Uses of clozapine

The Food and Drug Administration (FDA) approves prescription drugs such as clozapine for certain conditions. Approved uses for clozapine are described below.

Use for schizophrenia

Doctors may prescribe clozapine tablet and orally disintegrating tablet for treating schizophrenia. It’s used for this purpose in adults. It’s usually prescribed as a long-term treatment.

With schizophrenia, the cause is unknown. Symptoms of schizophrenia can be devastating and usually start in the late teens to early 30s. They include:

• hallucinations (sensory experiences, such as seeing or hearing things that seem real but are not)
• delusions (believing things that are obviously false)
• disorganized thoughts
• withdrawal from family and friends
• inability to enjoy life

Clozapine is used for treatment-resistant schizophrenia. This is schizophrenia that does not respond to other antipsychotic drugs.

Use for reducing suicidal behavior in certain people

Doctors may prescribe clozapine tablet and orally disintegrating tablet to reduce suicidal behaviors in certain people. It’s used for this purpose in adults. It’s usually prescribed as a long-term treatment.

Clozapine is approved for use in two groups of people with suicidal behavior. These are:

• people with schizophrenia who have had suicidal behavior in the past
• people with schizoaffective disorder who have had suicidal behavior in the past

Schizoaffective disorder also has symptoms of hallucinations, delusions, and withdrawal from family and friends. But it also has symptoms of mania.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

• Ask the tough question: “Are you considering suicide?”.
• Listen to the person without judgment.
• Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
• Stay with the person until professional help arrives.
• Try to remove any weapons, medications, or other potentially harmful objects.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Click here for more links and local resources.

Interactions and warnings for clozapine

Below you’ll find information about clozapine’s possible interactions and warnings.

Interactions of clozapine

Certain things may affect how a drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you take clozapine, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription or over-the-counter drugs
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for clozapine” section below.

Warnings for clozapine

Clozapine should not be taken by certain people.

Boxed warnings

Clozapine has boxed warnings about the following risks. Boxed warnings are the most serious warnings from the Food and Drug Administration (FDA).

To learn more about these warnings, read below. You can also talk with your doctor or pharmacist.

Risk of severe low neutrophil levels. With low neutrophil levels, you don’t have enough white blood cells to fight off infections. This side effect was rarely reported in studies of clozapine.

Symptoms may include fever, sinus infections, skin infections, pneumonia, and other infections.

If you have concerns about severely low neutrophil levels, tell your doctor. They’ll likely recommend frequent blood tests to check them.

Due to these risks, the drug is available only through the Clozapine risk evaluation and mitigation strategies (REMS) program. The FDA requires REMS programs for certain drugs to help make sure they’re prescribed safely.

Risk of serious low blood pressure, slow heart rate, and fainting. Low blood pressure and slow heart rate can cause fainting and falls. This side effect was rarely reported in studies of clozapine. In the rare cases that it happens, it’s usually when starting clozapine or when increasing the dose.

Symptoms may include feeling lightheaded or dizzy, especially when standing up.

If you have low blood pressure, a slow heart rate, or faint, tell your doctor. They’ll likely recommend a lower dose of clozapine and to increase your dose slowly.

Risk of seizures. With seizures, your muscles may become stiff. You may start jerking uncontrollably or lose consciousness. This side effect was rarely reported in studies of clozapine.

If you have concerns about seizures, tell your doctor. They’ll likely recommend a lower dose of clozapine and to increase your dose slowly.

Risk of serious conditions of the heart muscle. With serious conditions of the heart muscle, you may have chest pain, palpitations, high heart rate (even at rest), fever, and flu-like symptoms. This side effect was rarely reported in studies of clozapine.

If you experience a serious condition of your heart muscle, tell your doctor. They’ll likely recommend that you stop taking clozapine.

Increased risk of death in older adults with dementia-related psychosis. There is an increased risk of death in older adults with dementia-related psychosis who take clozapine.  This side effect was commonly reported in studies of clozapine.

Though the causes of death varied, most were from:

• heart problems, such as heart failure or sudden death
• infections such as pneumonia

If you have concerns about an increased risk of death in older adults with dementia-related psychosis, tell your doctor. They’ll likely recommend that you do not take or stop taking clozapine.

Other warnings

Clozapine could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether clozapine is a safe option for you. These warnings may differ based on the form of clozapine you take.

Ask your doctor about specific warnings for clozapine, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Clozapine can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to clozapine or any of its ingredients, your doctor will likely not prescribe clozapine. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• serious skin reaction called Stevens-Johnson syndrome, which may be life threatening
• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to clozapine, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Overdose of clozapine

If you take clozapine by mouth you should not take more clozapine than your doctor prescribes. For some drugs, doing so may lead to harmful effects or overdose.

If you think you’ve taken too much clozapine, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Pregnancy or breastfeeding and clozapine

Information about clozapine and pregnancy and breastfeeding is described below.

Clozapine and pregnancy

There are risks to taking clozapine during pregnancy. But there are also risks with having untreated schizophrenia or suicidal behavior while pregnant. (Keep in mind that clozapine is used for treating schizophrenia or suicidal behavior.)

If you’re planning a pregnancy or can become pregnant, talk with your doctor about schizophrenia or suicidal behavior treatment options during pregnancy. Together, you can discuss the risks and benefits of your treatment options and decide whether or not you should take clozapine during pregnancy.

Clozapine and breastfeeding

Clozapine should not be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication. Your doctor may recommend other ways to feed your child during treatment with clozapine.

What to ask your doctor

Let your doctor know if you have questions about clozapine or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• What should I do if I can’t afford my medication?
• What testing do I need while taking clozapine?
• How long does it take for clozapine to start working?

Resources

• Clozapine tablet. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/5021d643-32d2-4167-b5d8-90870e68a787/spl-doc
• Clozapine — clozapine tablet, orally disintegrating. (2022). https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=6fccf4f7-2e30-4272-9800-225aaef20584&type=display
• Clozaril (clozapine) tablets, for oral use. (2020). https://www.accessdata.fda.gov/drugsatfda_docs/label/2020/019758s095lbl.pdf
• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.