Despite the risk for numerous side effects, many side effects can be managed while continuing to take clozapine. Neutropenia and agranulocytosis
Clozapine Induced Neutropenia (CIN) occurs in approximately 3.8% of cases and Clozapine Induced Agranulocytosis (CIA) in 0.4%. These are potentially serious side effects and agranulocytosis can result in death. To mitigate this risk clozapine is only used with mandatory  absolute neutrophil count (ANC) monitoring (neutrophils are the most abundant of the granulocytes); for example, in the United States, the Risk Evaluation and Mitigation Strategy (REMS). The exact schedules and blood count thresholds vary internationally and the thresholds at which clozapine can be used in the U.S. has been lower than those currently used in the U.K. and Australasia for some time. The effectiveness of the risk management strategies used is such that deaths from these side effects are very rare occurring at approximately 1 in 7700 patients treated. Almost all the adverse blood reactions occur within the first year of treatment and the majority within the first 18 weeks. After one year of treatment these risks reduce markedly to that seen in other antipsychotic drugs 0.01% or about 1 in 10,000 and the risk of death is markedly lower still. When reductions in neutrophil levels are noted on regular blood monitoring then, depending on the value, monitoring may be increased or, if the neutrophil count is sufficiently low, then clozapine is stopped immediately and can then no longer be used within the medicinal licence. Stopping clozapine almost always results in resolution of the neutrophil reduction.
Central nervous system
CNS side effects include drowsiness, vertigo, headache, tremor, syncope, sleep disturbances, nightmares, restlessness, akinesia, agitation, seizures, rigidity, akathisia, confusion, fatigue, insomnia, hyperkinesia, weakness, lethargy, ataxia, slurred speech, depression, myoclonic jerks, and anxiety. Rarely seen are delusions, hallucinations, delirium, amnesia, libido increase or decrease, paranoia and irritability, abnormal EEG, worsening of psychosis, paresthesia, status epilepticus, and obsessive compulsive symptoms. Similar to other antipsychotics clozapine rarely has been known to cause neuroleptic malignant syndrome. Urinary incontinence
Clozapine is linked to urinary incontinence, though its appearance may be under-recognized. Withdrawal effects
Abrupt withdrawal may lead to cholinergic rebound effects, such as indigestion, diarrhea, nausea/vomiting, overabundance of saliva, profuse sweating, insomnia, and agitation. Abrupt withdrawal can also cause severe movement disorders, catatonia, and psychosis. Doctors have recommended that patients, families, and caregivers be made aware of the symptoms and risks of abrupt withdrawal of clozapine. When discontinuing clozapine, gradual dose reduction is recommended to reduce the intensity of withdrawal effects. Weight gain and diabetes
In addition to hyperglycemia, significant weight gain is frequently experienced by patients treated with clozapine. Impaired glucose metabolism and obesity have been shown to be constituents of the metabolic syndrome and may increase the risk of cardiovascular disease. The data suggest that clozapine may be more likely to cause adverse metabolic effects than some of the other atypical antipsychotics. Pneumonia
International adverse drug effect databases indicate that clozapine use is associated with a significantly increased incidence of and death from pneumonia and this may be one of the most significant adverse events.