Clozapine is one of the most effective antipsychotic drugs. On the other hand, it can cause serious side effects which have to be monitored. An adverse effect is myocarditis, a type B Clozapine reaction that can be fatal if it is not early diagnosed.

To report a case of a patient with Clozapine induced myocarditis.

A 48 years old women with a schizoaffective disorder was admitted to our Hospital due to a clinical decompensation. She had a manic episode with psychotic symptoms (persecutory delusions and auditive hallucinations). Clozapine was introduced after there were no improvement with Olanzapine, Risperidone and Valproic Acid. A dose increase was made reaching 100 mg/day the first week and 200 mg/day the second week. The third week she started with a 39ºC fever, decreased oxygen saturation, leukocytosis (9560 103/mm3), elevated PCR (210 mg/l) and elevated troponins (52,88 ng/l). EKG and other medical tests did not show alterations. There was not found a clear etiology, so Clozapine was retired as a cautionary measure. The differential diagnosis for etiology included viral infections, Clozapine induced myocarditis or idiopathic.

A few days after the withdrawal of Clozapine, cardiac symptoms improved, suggesting it was the most probable etiology.

Although it is not very likely to occur, it is important to consider myocarditis as a sever Clozapine side effect.

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