Clozapine (Oral)

Clozapine is also known under US brand names, Clozaril, FazaClo, and Versacloz. It is a drug that is used to treat severely ill patients who suffer from schizophrenia when other medications have not worked.


Clozapine is a drug used to treat severely ill patients who suffer from schizophrenia whom other medications have not worked well for. It's also used to lower the intensity of hallucinations and lessen the risk of suicidal behavior in those with schizoaffective or schizophrenia disorder. Clozapine is a psychiatric medication that works by helping to restore the balance of certain natural substances (neurotransmitters) in the brain. This medication should not be used to treat behavioral issues in older adults who suffer from dementia. This medication is only available via a restricted program and you may be asked to read and sign papers that explain the process of the medicine, how it works and some of the unwanted side effects that come with it. This drug is available in the following dosage forms: tablet, disintegrating tablet, and suspension.

Condition(s) treated?

  • Suicidal Behavior in Schizophrenia
  • Suicidal Behavior in Schizoaffective Disorder
  • Treatment-Resistant Schizophrenia
  • Mania associated with Bipolar Disorder
  • Bipolar Disorder in Remission

Type of medicine?

  • Oral tablet

Side Effects

Along with its intended effects, the use of clozapine can produce some unwanted side effects. Not all of these side effects may occur, but if they do, they may need medical attention.

If you suffer from any of the following side effects whilst taking clozapine, contact your doctor or a healthcare professional immediately.

More common

  • Faintness, dizziness or lightheadedness when getting up suddenly from a sitting or lying position
  • Confusion
  • Fast, pounding, or irregular heartbeat or pulse
  • Fainting
  • Blurred vision
  • Sleepiness or unusual drowsiness
  • Fever
  • Shakiness in the arms, legs, feet or hands
  • Sweating
  • Unusual weakness or tiredness
  • Shaking or trembling of the hands or feet

Less common

  • Tarry, black stools
  • Anxiety
  • Convulsions
  • Chills
  • A cough or hoarseness
  • Labored or difficult breathing
  • Decrease in the frequency of urination
  • Chest pain
  • Decrease in urine volume
  • Difficulty in passing urine or dribbling
  • Dry mouth
  • Discouragement
  • Feeling empty or sad
  • Loss of bladder control
  • General feeling of weakness or tiredness
  • Fever with or without chills
  • Frequent strong or increased urge to urinate
  • Headache
  • Lack of appetite
  • Hyperventilation
  • Irritability
  • Loss of interest or pleasure
  • Muscle spasm or jerking of the arms or legs
  • Side or lower back pain
  • Difficult or painful urination
  • Restlessness or need to keep moving
  • Pounding in the ears
  • Severe or continuing headache
  • Sore throat
  • Unsteady or shaky walk
  • Slurred speech
  • Ulcers, sores, or white spots on the lips or in the mouth
  • Sudden loss of consciousness
  • Sudden jerky movements of the body
  • Tightness in the chest
  • Swollen glands
  • Throat discomfort
  • Trouble concentrating
  • Trembling, unsteadiness or other problems with muscle control or coordination
  • Trouble sleeping


  • Absence of or decrease in movement
  • Dark urine
  • Change in appetite
  • Decreased sexual ability
  • Increased sweating
  • Fast or difficult breathing or sudden shortness of breath
  • Increased thirst
  • Puckering or lip smacking
  • Increased urination
  • Muscle stiffness
  • Puffing of the cheeks
  • Nausea
  • Rapid or worm-like movements of the tongue
  • Uncontrolled chewing movements
  • Pain or swelling in the leg
  • Uncontrolled movements of the legs and arms
  • Unusually pale skin
  • Unusual bruising or bleeding
  • Vomiting
  • Yellow skin or eyes
  • Weakness

Incidence not known

  • Stomach or abdominal pain
  • Crawling, burning, itching, numbness, prickling, "pins and needles", or tingling feelings
  • Bloating
  • Clay-colored stools
  • Constipation
  • Diarrhea
  • Confusion as to place, time or person
  • An epileptic seizure that will not stop
  • Feeling that others can hear your thoughts
  • Feeling that others are controlling or watching your behavior
  • Seeing, feeling or hearing things that are not there
  • Inability to move the eyes
  • Holding false beliefs that cannot be changed by facts
  • Increased spasms or blinking of the eyelid
  • Indigestion
  • Joint pain
  • Itching or skin rash
  • Light-colored stools
  • Rhythmic movement of the muscles
  • Muscle twitching
  • Pains in the side, stomach or abdomen, possibly radiating to the back
  • Severe mood or mental changes
  • Swelling around the eyes
  • Sticking out of the tongue
  • Swelling of the body or feet and ankles
  • Unpleasant breath odor
  • Trouble with speaking
  • Unusual behavior
  • Unusual facial expressions
  • Unusual excitement, nervousness, or restlessness
  • Unusual weight gain
  • Vomiting of blood
  • Upper right abdominal or stomach pain

Some side effects that occur with clozapine do not require urgent medical attention. Rather they will begin to disappear or reduce as your body begins to adjust to the medication. If however, you are finding the side effects are disrupting your everyday life, you should contact a local pharmacist or your doctor for advice on ways to reduce or prevent some side effects.

More common

  • Sleepiness
  • Sour or acid stomach
  • A feeling of constant movement of self or surroundings
  • Belching
  • Heartburn
  • Relaxed and calm sensation of spinning

Less common

  • Problems or changes with discharge of semen
  • Blurred or loss of vision
  • Disturbed color perception
  • Halos around lights
  • Double vision
  • Inability to sit still
  • Muscle pain or ache
  • Increase in body movements
  • Muscle weakness
  • Night blindness
  • Overbright appearance of lights
  • Nightmares
  • Pain in the neck, back or legs
  • Severe muscle stiffness
  • Pain in the chest below the breastbone
  • Sore tongue
  • Tunnel vision
  • Stuffy nose
  • Unusual dullness, drowsiness, tiredness, weakness, or feeling of sadness
  • Sluggishness

Incidence not known

  • Blistering, peeling, or loosening of the skin
  • Increased sensitivity of the skin to sunlight
  • Hives
  • Prolonged or painful erection of the penis
  • Red, irritated eyes
  • Red skin lesions, often with a purple center
  • Reddening of the skin, especially around the ears
  • Severe sunburn
  • Severe stomach pain
  • Swelling of the salivary glands
  • Welting, sores or blisters
  • Swelling of the face, eyes or inside of the nose


The final dose given of this medication will depend on a number of factors. This includes your age, height, weight, the severity of your condition, your past medical history and your reaction to the first dose. The following doses are given as a typical standard of doses given to treat schizophrenia. You should never stop, start or change your dose because it does not reflect what is listed below. You should contact your doctor if you are concerned or have any questions or queries about dose changes.

Typical Adult Dose for Schizophrenia

An initial dose of 12.5 mg if given twice a day orally and a maintenance dose involves increasing the total daily dose in increments of 25- 50 mg per day to a target dose of 300 - 450 mg per day by the end of week two. These will be administered in divided doses. Any other dose increases are usually in increments of up to 100 mg once or twice a week.

The maximum dose given is 900 mg per day.

  • A low starting dose, divided doses, and gradual titration are needed to minimize the risk of bradycardia, orthostatic hypotension, and syncope.
  • When treatment is interrupted for two days or more, re-initiate with 12.5 mg dose once or twice a day. This will be based on individual tolerability. A dose that is restarted can be increased to a previously therapeutic dose at a quicker rate than it was for initial treatment.
  • This medication may be taken with or without food
  • If a dose is missed for longer than two days, the patient should be restarted at 12.5 mg once or twice a day Interactions

Interactions can happen with a variety of drugs causing serious side effects or limiting the effectiveness of clozapine in treatment. It's therefore essential that you inform your doctor or a healthcare professional of all the drugs you are currently taking. This should include prescription and non-prescription drugs, herbal products, and all vitamins. You should also inform them of any other medical conditions you currently suffer from or have suffered from in the past. This should include any medical conditions that run in the family history.

Sometimes two medications will be used together because it is the best option for your treatment, despite the interaction. If this is the case, your doctor may alter the dose or frequency of either medication.

Using this medication with any of the following drugs is not recommended. Your doctor may avoid treating you with this medication at all or change some of the other drugs you are taking. Let your doctor know if you are taking any of the following drugs listed below. Do not stop, start or change doses without prior confirmation and advice from your doctor or a healthcare professional.

  • Amifampridine
  • Bepridil
  • Cisapride
  • Amisulpride
  • Bromopride
  • Dronedarone
  • Ketoconazole
  • Droperidol
  • Mesoridazine
  • Nelfinavir
  • Metoclopramide
  • Pimozide
  • Saquinavir
  • Piperaquine
  • Thioridazine
  • Sparfloxacin
  • Terfenadine
  • Ziprasidone

The use of this drug with any of the following medications is not recommended, but in rare cases, it may be required. If you are prescribed both medications, your doctor may alter the dose or change the frequency in which you use either medication.

  • Abiraterone
  • Amiodarone
  • Alfentanil
  • Alfuzosin
  • Amoxapine
  • Anagrelide
  • Amprenavir
  • Apomorphine
  • Aripiprazole
  • Aprepitant
  • Armodafinil
  • Asenapine
  • Arsenic Trioxide
  • Astemizole
  • Atazanavir
  • Azithromycin
  • Besifloxacin
  • Balofloxacin
  • Bedaquiline
  • Boceprevir
  • Bosentan
  • Bromazepam
  • Buprenorphine
  • Buspirone
  • Bupropion
  • Buserelin
  • Butorphanol
  • Chloroquine
  • Carbamazepine
  • Ceritinib
  • Chlorpromazine
  • Cinacalcet
  • Cimetidine
  • Cinoxacin
  • Clarithromycin
  • Ciprofloxacin
  • Citalopram
  • Clobazam
  • Crizotinib
  • Cobicistat
  • Conivaptan
  • Cyclobenzaprine
  • Darunavir
  • Dabrafenib
  • Dasatinib
  • Degarelix
  • Delamanid
  • Deslorelin
  • Dexamethasone
  • Dihydrocodeine
  • Disopyramide
  • Diltiazem
  • Disulfiram
  • Dolasetron
  • Dofetilide
  • Domperidone
  • Donepezil
  • Doxorubicin Hydrochloride Liposome
  • Doxorubicin
  • Doxylamine
  • Enoxacin
  • Efavirenz
  • Enzalutamide
  • Escitalopram
  • Erythromycin
  • Famotidine
  • Ethinyl Estradiol
  • Etravirine
  • Fentanyl
  • Flecainide
  • Fingolimod
  • Flibanserin
  • Fluorouracil
  • Flumequine
  • Fluoxetine
  • Fosamprenavir
  • Fluvoxamine
  • Fosaprepitant
  • Gemifloxacin
  • Fosphenytoin
  • Gatifloxacin
  • Gonadorelin
  • Goserelin
  • Halofantrine
  • Granisetron
  • Histrelin
  • Hydrocodone
  • Hydroquinidine
  • Hydromorphone
  • Hydroxychloroquine
  • Hydroxyzine
  • Iloperidone
  • Ibutilide
  • Idelalisib
  • Imatinib
  • Itraconazole
  • Indinavir
  • Ivabradine
  • Lapatinib
  • Leuprolide
  • Lomefloxacin
  • Levofloxacin
  • Lithium
  • Lopinavir
  • Mefloquine
  • Lumefantrine
  • Mate
  • Methoxsalen
  • Meperidine
  • Methadone
  • Metronidazole
  • Miconazole
  • Mexiletine
  • Mibefradil
  • Mifepristone
  • Mizolastine
  • Milnacipran
  • Moricizine
  • Modafinil
  • Montelukast
  • Morphine
  • Moxifloxacin
  • Morphine Sulfate Liposome
  • Nadifloxacin
  • Nafcillin
  • Nafarelin
  • Nalidixic Acid
  • Nevirapine
  • Nefazodone
  • Nilotinib
  • Ofloxacin
  • Norfloxacin
  • Octreotide
  • Omeprazole
  • Oxolinic Acid
  • Oxcarbazepine
  • Oxycodone
  • Paliperidone
  • Oxymorphone
  • Pasireotide
  • Panobinostat
  • Paroxetine
  • Pazufloxacin
  • Pazopanib
  • Pefloxacin
  • Peginterferon Alfa-2b
  • Pentazocine
  • Pentamidine
  • Perflutren Lipid Microsphere
  • Perphenazine
  • Periciazine
  • Phenobarbital
  • Pimavanserin
  • Phenylpropanolamine
  • Phenytoin
  • Pipemidic Acid
  • Pixantrone
  • Pitolisant
  • Prednisone
  • Prochlorperazine
  • Procainamide
  • Promethazine
  • Prulifloxacin
  • Propranolol
  • Protriptyline
  • Quetiapine
  • Quinine
  • Quinidine
  • Ranolazine
  • Regorafenib
  • Rifampin
  • Remifentanil
  • Rifabutin
  • Rifapentine
  • Rufinamide
  • Rosoxacin
  • Rufloxacin
  • Sertindole
  • Salmeterol
  • Sertraline
  • Sodium Phosphate, Dibasic
  • Sevoflurane
  • Sodium Phosphate
  • Sodium Phosphate, Monobasic
  • Solifenacin
  • Sotalol
  • Sorafenib
  • St John's Wort
  • Sulpiride
  • Sufentanil
  • Sunitinib
  • Tapentadol
  • Tacrolimus
  • Tegafur
  • Telaprevir
  • Telavancin
  • Tetrabenazine
  • Telithromycin
  • Terbinafine
  • Thiabendazole
  • Ticlopidine
  • Ticagrelor
  • Tiotropium
  • Topiramate
  • Tipranavir
  • Toremifene
  • Trifluoperazine
  • Trazodone
  • Trimipramine
  • Vandetanib
  • Triptorelin
  • Vemurafenib
  • Vardenafil
  • Vinflunine
  • Verapamil
  • Zotepine
  • Voriconazole
  • Zileute
  • Zuclopenthixol

Other Interactions

Some medications cannot be used at or around the time of eating certain types of food or eating in general since interactions may occur. Using tobacco or alcohol with some medications can also cause interactions.

Using Clozapine with any of the following foods/drinks is usually not recommended, however, in some cases, it may be unavoidable. If used together, your doctor may alter the dose or how the frequency in which you use, or give special instructions about the use of alcohol, food or tobacco.

  • Grapefruit Juice
  • Tobacco
  • Caffeine

Other Medical Problems

If you suffer from other medical problems, they could affect the effectiveness of = =. Ensure you inform your doctor if you have any other medical conditions, especially:

  • Blood clotting problems (eg, pulmonary embolism, deep vein thrombosis)
  • Dehydration
  • Blood vessel problems (poor circulation)
  • Head injury or a history of head injury
  • A history of alcohol abuse
  • Heart attack recently or in the past
  • Heart rhythm problems (eg, long QT syndrome, arrhythmia or slow heart rate)
  • Heart disease (eg, myocarditis, cardiomyopathy)
  • Heart failure
  • Hypokalemia (low potassium in the blood)
  • Hypotension (low blood pressure)
  • Hypomagnesemia (low magnesium in the blood)
  • Hypovolemia (low blood volume)
  • Bowel problems (eg, constipation)
  • Stroke, or a history of a stroke: the use of this medication alongside a stroke could cause side effects to worsen.
  • Diabetes (type 1 or type 2)


Allergic reactions

Before you take clozapine, inform your pharmacist or doctor if you are allergic to it or any other allergies you may have, including to food, animals, preservatives, dyes etc. This drug may contain inactive ingredients, which could cause an allergic reaction or other problems. Speak with your pharmacist for more information.

Use during pregnancy and breastfeeding

This drug is under pregnancy category B. During pregnancy, this medication should be used only when clearly needed. A baby who is born to a mother who has used this drug during the last three months of pregnancy could develop symptoms including shakiness, muscle stiffness, feeding/breathing difficulties, drowsiness or constant crying. If you recognize any of these symptoms in your newborn, particularly during their first month, seek urgent medical attention.

Since untreated mood/meta problems (such as schizophrenia, schizoaffective disorders) can be a serious condition, don't stop taking this medication unless you have been directed to do so by a healthcare professional or your doctor. If you are planning a pregnancy, become pregnant, or think you may be pregnant, you should discuss immediately, the benefits and risk associated with using this medication during pregnancy with your doctor asap.

With regards to breastfeeding, this drug may pass into breast milk and have undesirable effects on an infant. Breastfeeding is therefore not recommended while taking this medication. You should consult your doctor before breastfeeding.

Use in pediatric patients

Studies have not been performed on the relationship of age to the effects of this drug on the pediatric population. This, therefore, means efficacy and safety have not been established.

Use in the geriatric population

Studies performed to date have not indicated any geriatric-specific problems that could reduce the usefulness of this drug in the elderly. However, older patients are more likely to have trouble passing urine, constipation, uncontrolled movements, or age-related kidney, liver or heart problems, which may require extra caution in those who are receiving clozapine.

Do not stop taking clozapine without speaking with your doctor first. If you stop this medication suddenly, some conditions may become worse. Also, you could experience symptoms such as a headache, severe sweating, nausea, diarrhea, and vomiting. To avoid these symptoms when you are stopping treatment with this clozapine, your doctor may reduce your dose gradually. Report any new or worsening symptoms urgently.

This use of clozapine can make you drowsy or dizzy and cause blurred vision. Do not use machinery, drive or do any activity that requires clear vision or alertness until you are sure you can perform these activities safely. Avoid alcohol.

Inform your doctor if you are descendent of Ashkenazi Jews because you may have a greater risk of a drop in your white blood cells.


  • This medication should be kept out of the reach of children.
  • Do not keep medication that is no longer need or outdated.
  • Do not share this medication with anyone else under any circumstances.
  • For advice on the correct disposal of this medication, you should contact your local pharmacist or healthcare professional.
  • This medication should be stored in a closed container at room temperature, away from moisture, heat, and light. This medication should not be allowed to freeze.


When used correctly, Clozapine is successful in treating schizophrenia and other psychotic conditions, especially when previous drugs have not been successful. Be aware that it could take several weeks before the full benefit of this drug takes effect and you notice any positive changes. You should contact your doctor if you feel your conditions worsens or persists. There are many drugs and medical conditions that can limit the effectiveness of this drug, so it's therefore important that you tell your doctor of all medications you are currently taking, including any medical conditions you have suffered from in the past. This drug should not be used during pregnancy or whilst you are breastfeeding. Inform your doctor if you fall pregnant whilst taking this medication.