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Clozapine (Clozapine 100mg tablets)



Information specific to: Clozapine 100mg tablets when used in Schizophrenia and Psychosis.

Clozapine (Kloz-uh-peen) is a medicine which is used in schizophrenia.

The information in this Medicine Guide for clozapine varies according to the condition being treated and the particular preparation used.

Your medicine

Clozapine is used to treat schizophrenia. Clozapine is given to people when their previous treatments for schizophrenia have not been successful or when those treatments have caused bad side-effects. Clozapine is also used in people who have Parkinson's disease who suffer with psychosis and in whom other treatment has not been successful.

In schizophrenia there is a chemical imbalance in the brain. Clozapine blocks some of the effects of this imbalance and helps to treat the symptoms of schizophrenia such as hallucinations or delusions.

Clozapine has effects on the immune system. People who take Clozapine are prone to getting infections. You will need to have regular blood tests while you are taking Clozapine to see if it is having an effect on your immune system. When you first start taking Clozapine you will have to go for a blood test every week. After a while you will probably need to have fewer blood tests. For information on having blood tests while you are taking Clozapine speak to your prescriber or a member of your medical team.

Other information about Clozapine:

  • if you do not take Clozapine for more than two days in a row you will need to start taking it at a low dose and then the dose will need to be increased gradually like when you first started treatment with Clozapine. For more information about restarting treatment with Clozapine after you have missed some doses, speak to your prescriber or a member of your medical team
  • smoking may affect the level of Clozapine in your blood. If you stop smoking while taking Clozapine you should speak to a member of your medical team as the dose of Clozapine may need to be reduced
  • if you are changing from other oral antipsychotic preparations to Clozapine, your prescriber will gradually discontinue the other antipsychotic preparation before starting with Clozapine
  • your doctor may start you on a low dose of this medicine and then increase the dose depending on how you respond to treatment. This is in order to reduce the chance of side-effects
  • this medicine should be used for at least six months

Do not share your medicine with other people. It may not be suitable for them and may harm them.

The pharmacy label on your medicine tells you how much medicine you should take. It also tells you how often you should take your medicine. This is the dose that you and your prescriber have agreed you should take. You should not change the dose of your medicine unless you are told to do so by your prescriber.

If you feel that the medicine is making you unwell or you do not think it is working, then talk to your prescriber.

Whether this medicine is suitable for you

Clozapine is not suitable for everyone and some people should never use it. Other people should only use it with special care. It is important that the person prescribing this medicine knows your full medical history.

Your prescriber may only prescribe this medicine with special care or may not prescribe it at all if you:

  • are aged over 60 years
  • are allergic or sensitive to or have had a reaction to any of the ingredients in the medicine
  • are an alcoholic
  • are intoxicated with drugs
  • are unable to have regular blood tests
  • have a family history of heart disease
  • have brain or central nervous system problems
  • have dementia
  • have diabetes
  • have glaucoma
  • have had blood problems caused by Clozapine
  • have had recent surgery of the stomach
  • have kidney problems
  • have liver problems
  • have or have had blood problems
  • have or have had bone marrow problems
  • have or have had certain heart or circulation problems
  • have or have had epilepsy
  • have or have had gastrointestinal problems
  • have or have risk factors for thromboembolic problems
  • have prostate problems
  • have psychosis caused by drugs or other substances
  • have risk factors for developing diabetes such as having a family history of diabetes or being obese
  • have risk factors for stroke

Furthermore the prescriber may only prescribe this medicine with special care or may not prescribe it at all for someone who is under the age of 16 years or for someone who is in a coma.

As part of the process of assessing suitability to take this medicine a prescriber may also arrange tests:

  • to determine whether or not the medicine is suitable and whether it must be prescribed with extra care
  • to check that this medicine is not having any undesired effects

Over time it is possible that Clozapine can become unsuitable for some people, or they may become unsuitable for it. If at any time it appears that Clozapine has become unsuitable, it is important that the prescriber is contacted immediately.


Alcohol can interact with certain medicines.

In the case of Clozapine:

  • this medicine may interact with alcohol

You must not drink any alcohol if you are taking this medicine.


Medicines can interact with certain foods. In some cases, this may be harmful and your prescriber may advise you to avoid certain foods.

In the case of Clozapine:

  • this medicine interacts with caffeine

If your diet includes any of the above, speak to your prescriber or pharmacist for further advice.

Driving and operating machinery

When taking any medicine you should be aware that it might interfere with your ability to drive or operate machinery safely.

In the case of Clozapine:

  • this medicine could affect your ability to drive or operate machinery

You must not drive or operate machinery while you are taking Clozapine.

Family planning and pregnancy

Most medicines, in some way, can affect the development of a baby in the womb. The effect on the baby differs between medicines and also depends on the stage of pregnancy that you have reached when you take the medicine.

In the case of Clozapine:

  • you should only take this medicine during pregnancy if your doctor thinks that you need it
  • if you could become pregnant, you must use effective contraception or abstain from penetrative sex. You must contact your prescriber if you become pregnant, or think you have become pregnant while taking Clozapine
  • if you take this medicine during the late stages of pregnancy or during labour, your baby may have some problems or withdrawal symptoms from Clozapine and may need to have some monitoring after birth

You need to discuss your specific circumstances with your doctor to weigh up the overall risks and benefits of taking this medicine. You and your doctor can make a decision about whether you are going to take this medicine during pregnancy.

If the decision is that you should not have Clozapine, then you should discuss whether there is an alternative medicine that you could take during pregnancy.


Certain medicines can pass into breast milk and may reach your baby through breast-feeding.

Women who are taking Clozapine must not breast-feed. If you wish to breast-feed you should discuss with your prescriber whether there are any other medicines you could have. You should not stop this medicine without taking advice from your doctor.

Taking other medicines

If you are taking more than one medicine they may interact with each other. At times your prescriber may decide to use medicines that interact, in other cases this may not be appropriate.

The decision to use medicines that interact depends on your specific circumstances. Your prescriber may decide to use medicines that interact, if it is believed that the benefits of taking the medicines together outweigh the risks. In such cases, it may be necessary to alter your dose or monitor you more closely.

Tell your prescriber the names of all the medicines that you are taking so that they can consider all possible interactions. This includes all the medicines which have been prescribed by your GP, hospital doctor, dentist, nurse, health visitor, midwife or pharmacist. You must also tell your prescriber about medicines which you have bought over the counter without prescriptions.

The following medicines may interact with Clozapine:

  • adrenaline
  • caffeine
  • carbamazepine
  • chloramphenicol
  • cimetidine
  • ciprofloxacin
  • citalopram
  • co-trimoxazole
  • digoxin
  • erythromycin
  • fluoxetine
  • fluvoxamine
  • lithium
  • noradrenaline
  • omeprazole
  • paroxetine
  • penicillamine
  • phenylbutazone
  • phenytoin
  • rifampicin
  • sertraline
  • valproic acid
  • warfarin

The following types of medicine may interact with Clozapine:

  • alpha-adrenergics
  • antiarrhythmics
  • anticholinergics
  • antidepressants
  • antihistamines
  • antihypertensives
  • antiparkinsonian agents
  • azole antifungal agents
  • benzodiazepines
  • cytochrome P450 enzyme inducers
  • cytochrome P450 enzyme inhibitors
  • cytotoxics
  • highly protein bound agents
  • medicines that act on the central nervous system
  • medicines that affect electrolyte balance
  • medicines that are damaging to the bone marrow
  • medicines that can cause constipation
  • medicines that lower blood pressure
  • medicines that prolong the QTc interval
  • medicines which depress the CNS
  • monoamine oxidase inhibitors
  • narcotics
  • other antipsychotics
  • phenothiazines
  • protease inhibitors
  • psychotropics
  • pyrazolone analgesics
  • respiratory depressants
  • selective serotonin re-uptake inhibitors
  • sulphonamides

If you are taking Clozapine and one of the above medicines or types of medicines, make sure your prescriber knows about it.

Complementary preparations and vitamins

Medicines can interact with complementary preparations and vitamins. In general, there is not much information available about interactions between medicines and complementary preparations or vitamins.

If you are planning to take or are already taking any complementary preparations and vitamins you should ask your prescriber whether there are any known interactions with Clozapine.

Your prescriber can advise whether it is appropriate for you to take combinations that are known to interact. They can also discuss with you the possible effect that the complementary preparations and vitamins may have on your condition.

If you experience any unusual effects while taking this medicine in combination with complementary preparations and vitamins, you should tell your prescriber.

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