This article describes possible side effects of clozapine oral tablet. You can explore this overview article to learn more about clozapine, including the drug’s uses, side effects, ways to save on cost, and more.
Clozapine oral tablet is a generic version of the brand-name drug Clozaril. Clozapine also comes in a liquid suspension, but this form isn’t described in this article. To learn more about this form, talk with your doctor.
Boxed warnings
Clozapine oral tablet has boxed warnings about the following risks. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).
For details, see the “Side effects of clozapine in detail” section below.
Need a diagnosis or prescription quickly? For certain health conditions, Optum Perks offers personalized on-demand care with no appointment required. For $25, answer a few questions online and receive a diagnosis and treatment plan from a board certified healthcare professional in 15 minutes or less. Get started here.
More common side effects of clozapine
Clozapine oral tablet may cause mild or serious side effects. Below are some of the more common side effects of this medication.
Commonly reported side effects of clozapine oral tablet include:
- sleepiness
- dizziness or vertigo (spinning sensation)
- headache
- tremor
- fast heart rate
These side effects were reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Mild side effects of clozapine
Clozapine may cause certain mild side effects. Usually, mild side effects are temporary and can be easily managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.
Mild side effects of clozapine oral tablet that occurred in studies include:
- sleepiness
- dizziness or vertigo (spinning sensation)
- headache
- tremor
- fast heart rate
- low blood pressure
- fainting
- increased saliva
- sweating
- dry mouth
- changes in vision
- constipation
- nausea
- fever
- high blood pressure
- vomiting
- disturbed sleep
- nightmares
- restlessness
- mild allergic reaction*†
* To learn more about this side effect, see the “Side effects of clozapine in detail” section below.
† An allergic reaction is possible with clozapine oral tablets and clozapine oral tablets. But it’s unclear whether it occurred in the drug’s studies for clozapine oral tablets and clozapine orally disintegrating tablets
These side effects were reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Clozapine oral tablet may cause more mild side effects than those listed above. For details, see the drug’s prescribing information for clozapine oral tablets and clozapine orally disintegrating tablets.
Serious side effects of clozapine
Clozapine may cause certain serious side effects. If you have any serious side effects from clozapine oral tablet, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.
After the FDA approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with clozapine.
Serious side effects of clozapine oral tablet that occurred in studies include:
* To learn more about this side effect, see the “Side effects of clozapine in detail” section below.
† Clozapine oral tablets and clozapine orally disintegrating tablets have a boxed warning for this side effect. A boxed warning is the most serious warning from the FDA. To learn more, see the “Side effects of clozapine in detail” section below.
‡ An allergic reaction is possible with clozapine oral tablets and clozapine orally disintegrating tablets. But it’s unclear whether it occurred in the drug’s studies for clozapine oral tablets and clozapine orally disintegrating tablets.
These side effects were reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Suicide prevention
If you or someone you know is in crisis and considering suicide or self-harm, please seek support:
If you’re calling on behalf of someone else, stay with them until help arrives. You may remove weapons or substances that can cause harm if you can do so safely.
If you are not in the same household, stay on the phone with them until help arrives.
Download the free Optum Perks Discount Card to save up to 80% on some prescription medications.
Common questions about side effects of clozapine
Here are answers to some common questions about side effects of clozapine oral tablet. If you have other questions, talk with your doctor or pharmacist.
Does clozapine cause long-term side effects?
Yes, in some cases clozapine oral tablet may cause long-term side effects. These can last for a while after you’ve stopped taking the drug.
Examples of long-term side effects reported with clozapine oral tablet include:
These side effects were reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Talk with your doctor to learn more about these side effects and how to manage them. Ask your doctor for more information about how long these side effects of clozapine may last.
Is clozapine safe for older adults?
It may be. But older adults (adults ages 65 years and older) may be at higher risk of certain side effects. These include low blood pressure that occurs upon standing, fast heart rate, constipation, problems emptying your bladder, and tardive dyskinesia (movement disorder that causes involuntary movements).
Due to this risk, doctors may prescribe a lower dosage of clozapine oral tablet for older adults.
If you have concerns about taking clozapine given your age, talk with your doctor.
Can clozapine be used for bipolar disorder? If so, are the side effects similar to when it’s used for schizophrenia?
Maybe. But clozapine isn’t approved to treat bipolar disorder. It’s approved to treat schizophrenia and suicidal behavior.
In some cases, doctors may prescribe clozapine off-label for bipolar disorder. With off-label use, doctors prescribe a drug for a purpose other than what it’s approved for. Clozapine has not been studied in people with bipolar disorder. So, the specific side effects of clozapine when used for this condition are not known. However, it’s possible that they will be similar to those seen when the drug is used for schizophrenia.
If you have questions about treatment options for bipolar disorder, talk with your doctor.
Side effects of clozapine in detail
Below you’ll find details on some of the side effects of clozapine oral tablet.
Boxed warnings
Clozapine oral tablet has boxed warnings about certain risks. A boxed warning is the most serious warning from the FDA.
To learn more about these warnings, read below. You can also talk with your doctor or pharmacist.
Risk of severe, low neutrophil levels (a type of white blood cell)
In studies, severely low neutrophil levels were rare in people taking clozapine oral tablet. Neutrophils are a type of white blood cell that helps your immune system protect the body from infections. With low levels of neutrophils, your body can’t respond against infections as well. This increases the risk of serious and life threatening infections.
This side effect was reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
With low neutrophil levels, you are at risk of serious infections. Symptoms of infections may include:
- fever
- weakness
- lethargy
- sore throat
Ways to manage
Due to this risk, doctors will order frequent blood tests to monitor your neutrophil levels. If your neutrophil levels are too high, your doctor will likely have you pause or permanently stop your clozapine treatment.
You’ll also need to be enrolled in the Clozapine Risk Evaluation and Mitigation Strategy (REMS) Program while you’re taking this medication. The Clozapine REMS Program helps doctors and pharmacists work together to help reduce the risk of low neutrophil levels in people taking clozapine.
If you experience symptoms of an infection, tell your doctor. They’ll likely give you treatment for your infection.
Risk of serious low blood pressure, slow heart rate, and fainting
In studies, serious low blood pressure, slow heart rate, and fainting were rare in people taking clozapine oral tablet. This side effect may be serious.
Clozapine oral tablet can cause a drop in blood pressure upon standing. This is called orthostatic hypotension. It can also cause slow heart rate and fainting. All of these side effects can lead to falls, which can cause fractures or other injuries. The risk is highest when you first start treatment or when your dosage is increased.
This side effect was reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Symptoms may include dizziness, lightheadedness, or unsteadiness when standing up.
Certain factors can increase this risk with clozapine oral tablets. These include:
Ways to manage
If you experience symptoms of low blood pressure or slow heart rate, or if you faint, tell your doctor. They may lower your dosage of clozapine oral tablet.
Risk of seizures
In studies, seizures occurred in people taking clozapine oral tablet. This side effect may be serious.
This side effect was reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
With seizures, there is a disruption in the electrical activity of the brain. Seizures can cause dramatic symptoms, subtle symptoms, or no symptoms at all. If you have symptoms, they may include:
- stiffening of muscles
- repetitive jerking
- loss of consciousness
- drooling or frothing at the mouth
- biting your tongue
- rapid eye movements
Certain factors can increase the risk of seizures with clozapine oral tablets. These include:
- taking higher dosages of clozapine oral tablets
- history of a head injury
- history of seizures
- alcohol abuse
- taking other medications that make seizures more likely
Ways to manage
Due to this risk, use caution when doing activities where loss of consciousness could cause serious harm. Examples include driving, swimming, and climbing.
To lower the risk of seizures, doctors will likely prescribe a lower dosage of clozapine and increase the dosage slowly over time.
Risk of serious heart problems
In studies, serious heart problems occurred in people taking clozapine oral tablet. This side effect may be serious and life threatening. Most cases happened within the first two months of treatment.
This side effect was reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Symptoms may include:
- chest pain
- fast heart rate
- palpitations
- shortness of breath
- fever
- flu-like symptoms
- low blood pressure
Ways to manage
If you experience symptoms of heart muscle problems, tell your doctor right away. They’ll likely recommend that you stop taking clozapine oral tablets.
Increased risk of death in older adults with dementia-related psychosis
Clozapine oral tablets can increase the risk of death in older adults (adults ages 65 years and older) with dementia-related psychosis. Dementia is a medical condition that causes memory problems. Psychosis can be a complication of dementia.
This side effect was reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Ways to manage
If you have concerns about dementia-related psychosis, tell your doctor. They’ll likely recommend that you do not take clozapine oral tablets.
Tardive dyskinesia
In studies, tardive dyskinesia was rare in people taking clozapine oral tablet. This side effect may be serious.
Tardive dyskinesia is a movement disorder that causes involuntary, repetitive movements, such as blinking frequently, smacking your lips, or sticking out your tongue.
In most cases, tardive dyskinesia will go away if you stop taking clozapine oral tablet But there is a chance it can be permanent. The risk of tardive dyskinesia and the chance that it can cause permanent effects increases the longer you take clozapine oral tablet and the higher dosages you take.
This side effect was reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Ways to manage
If you experience symptoms of tardive dyskinesia, tell your doctor. They can help determine if you should stop taking clozapine oral tablets.
Neuroleptic malignant syndrome
In studies, neuroleptic malignant syndrome (NMS) was rare in people taking clozapine oral tablet. This side effect may be serious.
NMS is a serious and life threatening reaction to certain types of drugs, such as antipsychotics. It can happen if clozapine is taken alone or with other drugs that affect the central nervous system (CNS). (Your CNS is made up of your brain and spinal cord.)
This side effect was reported in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Symptoms of NMS may include:
- very high fever
- stiff muscles
- fast heart rate
- sweating
- difficulty swallowing
- rapid breathing
Ways to manage
If you experience symptoms of NMS, get emergency medical help right away. NMS is a medical emergency and requires immediate treatment. Doctors will likely have you stop taking clozapine and give you treatment for your symptoms.
For some people, clozapine oral tablets can cause an allergic reaction.
But it’s not clear whether this side effect occurred in studies of clozapine oral tablets and clozapine orally disintegrating tablets.
Symptoms can be mild or serious, and they may include:
- itchiness
- skin rash
- swelling under the skin, usually affecting eyelids, lips, hands, or feet
- swelling of the mouth, tongue, or throat, which can make it hard to breathe
- flushing (temporary warmth, redness, or deepening of skin color)
Ways to manage
For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.
For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening. If you’ve had a serious allergic reaction to clozapine oral tablets, your doctor may recommend taking a different medication instead.
Warnings for clozapine
Below are some factors you may want to discuss with your doctor before taking clozapine oral tablets.
Boxed warnings
This drug has boxed warnings about the following risks. A boxed warning is the most serious warning from the FDA.
For details, see the “Side effects of clozapine in detail” section above.
Other warnings
It may not be safe for you to take clozapine oral tablet if you have specific health conditions. These are sometimes called drug-condition interactions. Other things may also affect whether clozapine oral tablet is a safe treatment option for you.
Before taking clozapine oral tablet, tell your doctor about your health and medications you take. Things to consider include:
Clozapine and pregnancy
It’s not known whether clozapine oral tablet should be taken during pregnancy. If you’re planning a pregnancy or can become pregnant, talk with your doctor before taking this medication.
Clozapine and breastfeeding
Clozapine oral tablet 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.
Clozapine oral tablet is not known to interact with alcohol.
But your doctor may still recommend avoiding or limiting alcohol while taking clozapine oral tablet. Alcohol and clozapine can both cause drowsiness, dizziness, and impaired thinking and coordination. Combining the two can make these side effects worse.
If you drink alcohol, talk with your doctor about whether it’s safe to consume it during your treatment with clozapine oral tablet.
What to ask your doctor
This article describes common and serious side effects of clozapine oral tablet. If your doctor prescribes this medication, they can discuss possible side effects with you. Let your doctor know if you have concerns or questions about treatment with this medication.
Here’s a list of some possible questions you may want to ask your doctor:
- Is my risk of low blood pressure higher given my medical history?
- Will a higher dosage increase my risk of liver problems?
- How do the side effects of clozapine oral tablet compare with the side effects of other drugs used for my condition?
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.
