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Drug Class: Commonly Known As: Category:
Antipsychotics clozaril Adult

clozapine - What is it for

​Clozapine belongs to a class of medicine known as the second generation antipsychotics.

It is used to help treat symptoms of psychosis when other medicines have not worked. This includes but is not limited to symptoms of hallucinations, altered emotions, agitation and altered thought.

It may be given to you for other reasons. Do check with your doctor what you are taking this for.


clozapine - Side Effects, Precautions, and Contraindications

What side effects can clozapine cause?

Potential side effects

All medicines may cause side effects. However, many people do not experience them.

Most of the side effects listed here will improve with time. Speak with your doctor or pharmacist if they persist, become bothersome or worsen.


Side effectsWhat to do about it
Weight gainExercise regularly and maintain a healthy diet.

Increase your intake of fluids and include more fibre (vegetables and fruits) in your diet. Incorporate some exercise in your daily routine.

Consult your doctor or pharmacist if you require any laxatives.

Dry mouthSip water regularly. Sucking on sugar-free sweets or ice chips may help to alleviate symptoms. Avoid caffeine as it may worsen dry mouth.

Do not drive or operate any machinery.

Discuss with your doctor whether you can take your medicine at a different time of the day. 

DizzinessGet up slowly from a lying or sitting position
Excessive salivation (dribbling, a lot of saliva in your mouth)Propping up pillows while sleeping may help with this symptom. Consult your doctor for further advice.


Serious side effects

If you experience signs of allergy such as rashes, swelling of lips/face/throat and difficulty breathing, stop this medicine immediately and seek medical attention.

If you have symptoms such as changes in weight, passing of large amounts of urine and feelings of thirst and hunger all the time while taking this medicine, consult your doctor.

In rare cases, Clozapine may cause a condition known as agranulocytosis (low levels of white blood cells in the blood). You will need to have regular blood tests while taking this medicine. If you experience symptoms such as persistent fever, mouth ulcers and/or a sore throat, seek medical attention immediately.

In rare cases this drug may also affect the heart. Inform your doctor if you develop new or worsening palpitations, chest discomfort or pressure and/or unexplained fatigue and breathlessness.

Seizures (fits) may occur rarely while taking this medicine.

Clozapine may cause unusual movements involving the face or tongue, muscle stiffness, shakiness and unsteadiness on your feet. Please notify your doctor if this happens after taking this medicine.

A condition known as Neuroleptic Malignant Syndrome may occur rarely. Symptoms include but are not limited to fever, muscle rigidity, altered mental state/ consciousness and/or irregular blood pressure, heart rhythm and palpitations. If you develop any of these symptoms or other unexplained symptoms while taking this medicine, or require further information, consult your doctor.

Take note that the side effects listed here are not exhaustive. Do seek medical attention if you have other symptoms that you think may be related to this medicine.

Before taking clozapine , what precautions must I follow?

​What do I need to tell my doctor before I take this medicine?

  • Drug allergies.
  • Pre-existing medical conditions such as bone marrow disease, heart disease, myocarditis (inflammatory heart disease), diabetes, Parkinson's disease, seizures, stroke, blocked intestines, liver or kidney diseases, blood disorders, and prostate problems.
  • Whether you are taking any other medicines, supplements or traditional medicines. Some of them may affect how this medicine works.
  • For women: Tell your doctor if you are pregnant or breast-feeding or have plans to become pregnant. If you are pregnant and/or breastfeeding, your doctor would have discussed the potential benefits and side-effects of continuing this medicine with you but should you have further questions or concerns, do consult your doctor.


What food or medicine must I avoid when I take clozapine ?

​This medicine may interact with a number of other medicines. Inform your doctor if you are taking or intend to start taking other medicines or supplements.


clozapine - Dosage and How to Use

How should clozapine be used?

​Take this medicine exactly as prescribed by your doctor. Follow the instructions on the medicine label or as advised by the pharmacist.

Clozapine may be taken with or without food.

This medicine may not have an effect immediately. It may take up to a few weeks before this medicine can exert its full effects. Continue taking it regularly to benefit from it.

Do not stop taking this medicine even after you feel better. Your symptoms may return if this medicine is stopped too early. Check with your doctor on the duration of treatment that is suitable for you.

Do not stop taking this medicine abruptly or change the dose without consulting your doctor. You may experience unpleasant side effects if this medicine is stopped suddenly.

Avoid taking alcohol while taking this medicine.

What should I do if I miss a dose?

​Take the missed dose as soon as you remember. However, if it is close to the time for your next dose, skip the missed dose and take the next one at your usual timing.

Do not take 2 doses at the same time or extra doses.

If you have missed your dose for 2 days or more, consult your doctor again on the dose that you should be started back on.

What should I do if I overdose?

​If you take more of this medicine than prescribed by your doctor, consult your doctor or health care professional immediately.



clozapine - Handling

How should I handle clozapine safely?

clozapine - Storage

How should I store clozapine ?

;#Keep away from children;#Keep in a cool, dry place, away from direct sunlight;#Store at room temperature;#

How should I dispose of clozapine safely?

​Throw away any unused or expired medicines. Consult your medical professional if you are unsure with respect to how to safely dispose of any excess medicines/expired medicines.


clozapine - Additional Information

​What are the things I need to know or look out for while taking this medicine?

  • Avoid driving or any other activities that requires concentration until you see how this drug affects you.
  • Be careful in hot weather or while being active. Drink lots of fluids to stop fluid loss.
  • You may become more sensitive to sunlight. Ensure that you have adequate sun protection and avoid excessive sun exposure.
  • Smoking may affect this medicine. Inform your doctor if you are smoking.
  • Inform your other healthcare professionals that you are taking this medicine as well.
  • Discuss with your doctor or pharmacist before you take any other medicines or natural products.
  • Do not share your medicines with others.
  • Consult your doctor or pharmacist if you have any questions about your medicines.
  • Tags: Clozapine
  • Updated on 11/13/2018 12:00:00 AM
  • Article contributed by Changi General Hospital Changi General Hospital
The information provided is not intended as medical advice. Terms of use. Information provided by SingHealth

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