Free Consultation
1 (800) 301-3753

Clozaril (Clozapine) Side Effects, Withdrawal and FAQs

Clozaril (clozapine) belongs to a class of drugs called SGA’s or second generation antipsychotics.
Used in the treatment of certain mental conditions such as schizophrenia and psychosis, Clozaril is often prescribed only after other antipsychotics did not work or caused severe side effects.

Clozaril can cause certain side effects and withdrawal symptoms that may be difficult to navigate without assistance or guidance. The drug is not usually a first line treatment choice, but is more often used as an alternative choice where other prescriptions did not work or were not well tolerated due to severe reactions.

There are many important health reasons why it would be wise to research a drug before either starting or stopping a prescription drug, especially one as potent as Clozaril. Below you will find information on these and other topics that may be helpful in understanding more about Clozaril and how the drug works.

SPECIAL NOTE: As with all leftover, expired or unused prescription medications, please remember not to flush them or place them in regular garbage containers, and do not otherwise allow them to enter the water system in your community. Ask your local friendly pharmacist about the best way to dispose of medications so you can help protect the environment and the health of people around you.

What is Clozaril (Clozapine) Used For?

Clozaril is used in the treatment of certain mental disorders, where other (usually at least two) other antipsychotic medications have not worked, or where the side effects were too harsh and could not be tolerated by the patient. A candidate for a prescription of Clozaril may be someone diagnosed with treatment-resistant conditions such as:

  • Schizophrenia
  • Parkinson’s disease with severe thought disturbances
  • Schizoaffective disorder
  • Patients who are considered a significant risk for suicide because of a history of recurrent suicidal behavior
  • Borderline personality disorder presenting aggressive self-harm characteristics

Clozaril (Clozapine) Alternative Names and Slang

Clozaril is the brand name for the active ingredient, clozapine. Other brand names include Clopine, Clozapine Synthon, and FazaClo.

Clozaril (Clozapine) Side Effects

There are hundreds of known side effects for antipsychotic medications. We will list Clozaril-specific side effects both physiological (generally from highest risk on down), and psychological or mixed adverse effects, with the caution that this is not a complete list, as follows:

  • Risk of death in elderly patients with dementia (clozapine is not approved for this population)
  • Agranulocystosis: life-threatening lowering of white blood cell count often marked by lethargy, fever, weakness, or other signs of infection.
  • Eosinophilia: an abnormal increase in certain (two-lobed) white blood cells, often accompanied by asthma or other allergic symptoms resulting from toxic excretions of these immune cells as the Clozaril reaction turns these cells against their host, the patient.
  • Seizures: patients are advised not to drive or operate machinery, etc., due to risk of losing consciousness due to seizures on Clozaril.
  • Myocarditis: inflammation of the heart muscle, negatively affecting the electrical action and ability of the heart to pump blood. Clots can form in and around the heart leading to heart failure and death. The rate of myocarditis has been documented at from 17 – 322 times greater in patients on Clozaril than the general population. (1)
  • Orthostatic hypotension: drop in blood pressure associated with collapse and respiratory failure.
  • Cardiac events: such as tachycardia (elevated heart rate), ischemic changes (narrowing of the arteries), myocardial infarction (stoppage of blood flow within the heart), arrhythmias (irregular slowing or speeding up of heartbeat), congestive heart failure (progressive heart disease that weakens the heart), pericarditis (inflammation of the heart lining), pericardial effusions (collection of fluid in the lining of the heart), and sudden death.
  • Hyperglycemia: high blood sugar level that may emerge while on Clozaril
  • Diabetes Mellitus: condition where the body cannot utilize (metabolize) energy from food, resulting in fatigue, weight loss, headaches, tingling or numbness in the hands and feet, etc.
  • Neuroleptic Malignant Syndrome or NMS: a potentially fatal reaction to antipsychotic medications marked by irregular or racing heart beat and diaphoresis (heavy sweating), hyperpyrexia (body temperature over 106 F or 41.1 C), rigid muscles, altered mental state.
  • Tardive dyskinesia: a potentially irreversible condition linked to antipsychotic medications, involving involuntary dyskinetic (jerky, spasmodic) muscle motions. The hands and feet may appear to be thrashing in a quick or dance-like manner. Motions in the face and tongue appear as rolling or brief intermittent and irregular writhing or twisting characteristics.
  • Cardiomyopathy: refers to heart disease resulting in thickened or rigid heart muscles.
  • Pulmonary embolism: potentially fatal clotting causing a blockage in the lung which results in blockage of blood flow.
  • Hepatitis: Clozaril is associated with hepatitis whether or not a patient has had a history of liver disease before starting the drug.
  • Cognitive and Physical Motor Impairment: due to the sedating effects of Clozaril patients can experience significant cognitive and physical movement impairment on the drug.
  • Warning regarding pregnancy and nursing mothers: Clozaril can be excreted into the breast milk and should not be taken while nursing. No human studies have been performed on harm to the fetus, but the drug is not FDA recommended for pregnant women.
  • Impaired CNS: includes adverse side effects such as sedation, akathisia, vertigo, headache, tremor, nightmares, insomnia, agitation, convulsions, rigidity, slurred speech, etc.
  • Gastrointestinal: constipation, nausea, heartburn, abdominal pain, vomiting, diarrhea, anorexia, etc.
  • Autonomic Nervous System adverse effects: drooling, sweating, dry mouth, visual disturbances such as blurred vision, etc.
  • Other adverse effects: include fever, rash, sexual dysfunction, respiratory issues, shortness of breath, numbness in the tongue, weight gain, shortness of breath, nasal congestion, etc.

Clozaril (Clozapine) Withdrawal Symptoms

A significant number of individuals stop Clozaril due to side effects that become intolerable and outweigh any perceived benefit.

Except in circumstances where a life-saving intervention indicates sudden cessation, as discussed on more detail below in the section entitled “Discontinuing/Quitting Clozaril”, the FDA advises never to abruptly stop taking an antipsychotic agent such as Clozaril.

Withdrawal symptoms can be mild or severe, and may begin quite soon after forgetting a dose, or if tapering from Clozaril, or they may happen after a considerable lapse of time has occurred. Constant monitoring is considered a best practice for coming off antipsychotic medications.

When coming off Clozaril (clozapine), even at a slow taper, here are some of the reactions that can occur, and should be closely monitored:

  • Seizures
  • Sedation
  • Dizziness
  • Cardiovascular issues (i.e. tachycardia, blood pressure fluctations, etc.)
  • Nausea/vomiting and other gastrointestinal reactions
  • Excessive salivation (placing a towel on the pillow is recommended at night)
  • Headache
  • Tremor
  • Fever

Discontinuing/Quitting Clozaril (Clozapine)

There are circumstances where immediate withdrawal of Clozaril is medically needed as a life-saving intervention. These include potentially life-threatening adverse reactions to the drug which are delineated in detail under the adverse effects section, for instance cardiovascular compromise, risk of stroke, signs of tardive dyskinesia,  and other severe reactions.

In all other cases, gradual tapering methods are recommended for coming off the drug.

Always seek medical guidance and direction from your doctor before making changes to medications.

Clozaril (Clozapine) FAQs

Below you will find information concerning some of the most asked questions about the antipsychotic drug Clozaril (clozapine). It is always recommended to research a medication as thoroughly as possible before starting a prescription, and ask your doctor for more information about any questions you may have as regards your own health and medication history as well.

What Does Clozaril (Clozapine) Do to the Brain?

As with all psychoactive medications, there is much more that is yet to be discovered about their mechanics of action and how they work.

It has been found that Clozaril binds to certain receptors in the brain and central nervous system, and that this action alters the way the body and brain receive and transmit messages and commands along nerve channels.

There are various hypotheses concerning which receptors, and how strong or weak the reactions and interactions may be, but no definite answers have been as yet elucidated.(2)

Regarding the low and high moods of bipolar disorder, a potential theory to explain this phenomenon relates to the way that biological pathways of catecholamines function. Catecholamines include dopamine, norepinephrine, and adrenaline, otherwise known as excitatory neurotransmitters.

Dopamine is associated with reward, and a person experiencing an elevated sense of reward might be described as manic.

If something is present to impair the breakdown of dopamine, it follows that an excess of dopamine would result, and subsequently, a manic state. One such impairment may stem from certain enzymes not working efficiently, as stated in a study published by the National Institute of Mental Health. (3)

More research and clinical studies are needed to increase a general understanding of mental disorders and to continue to develop the most efficacious methods of treatment.

How Long Does Clozapine Stay in your System?

The drug stays in the system and can be tested as present in the urine for approximately 15 days, or around 360 hours. Based on the neuroadaptive effect and synaptic receptors that may have downregulated themselves as a result of the drug, the recalibrating time period back to pre-medicated states may be difficult to predict exactly.

When factoring “How long does Clozaril stay in your system?”, it may lead to a more pertinent question, which is, “How long are these neuroadaptive effects going to last?”.  There is no real obvious answer because there are several things that need to be considered, namely, individual genetics as well as external factors such as diet, duration of drug use, dosage, and similar. But it can be reasonably framed into months or even years. With the correct methods of treatment, this time dilation can be accelerated considerably. More information on this topic is given below in the “treatment” section of this article.

Treatment for Clozaril (Clozapine) Abuse and Addiction?

Our center specializes in treatment using holistic and natural methods for improving mental health. Where prescription drugs have not provided all the answers, or have caused unwanted adverse effects, we can help a person to safely and gently taper from and recover from these medications.

Dependence on psychiatric medications is sometimes compared synonymously to addiction. While the treatments for these conditions can overlap, there are also differences that must be taken into account in treating dependence that has developed when taking an antipsychotic medication, versus drug abuse and addiction.

Dependence on a potent antipsychotic drug must be treated with caution in respect to the risks that can accompany even a slow taper. We have helped clients overcome these formidable barriers utilizing a gentle taper, supported by nutrition-based, individualized, compassionate treatment methods.

Colonic hydrotherapy and other gentle remedies are available, which could be quite helpful where certain drugs, such as antipsychotics are prone to cause severe constipation. Constipation is not only uncomfortable, it can rob the body nutritionally, which once resolved can bring great relief and allow the body to begin to return to normal function again.

One of the most helpful treatments available to clients at ATMC is called holistic neurotransmitter replacement therapy. Using lab testing to isolate neurotoxic accumulations in the body, these are then purged using a highly effective but extremely gentle process of elimination. Nutritional support is also of great importance, as it gives the body what it needs to restore neurochemical balance in a natural way. These methods are all done in our beautiful inpatient treatment facility, resulting in a comfortable retreat-styled transformative experience.

More information is made freely available on request regarding our cutting edge, safe and comfortable methods that apply to medication withdrawal. We invite you to discover more about the effective and healthy protocols in use at the center for the benefit of all our clients at ATMC with whom we share the goal of recovery of natural mental health.


This content has been reviewed, and approved by a licensed physician.

Dr. John Motl, M.D.

Dr Motl is currently certified by the American Board of Psychiatry and Neurology in Psychiatry, and Board eligible in Neurology and licensed in the state of Arizona.  He holds a Bachelor’s of Science degree with a major in biology and minors in chemistry and philosophy. He graduated Creighton University School of Medicine with a Doctor of Medicine.  Dr. Motl has studied Medical Acupuncture at the Colorado School of Traditional Chinese Medicine and at U.C.L.A.

View Bio

Holistic Mental Health and Addiction Treatment Articles

News, media and up to date information on medications, symptoms and side effect, addiction and treatment for substance abuse from our expert staff.