Background: Clozapine is an antipsychotic agent used when patients experience excessive extrapyramidal side effects from other antipsychotic agents or for therapy resistant schizophrenia. However, clozapine is also known for its serious adverse effects e.g. granulocytopenia and agranulocytosis.
Case description: A 40-year-old male with known schizophrenia, presented with severe diarrhea and eosinophilia in the peripheral blood examination result, arising 2 weeks after starting clozapine. Histopathological examination demonstrated an eosinophilic colitis. After the patient discontinued clozapine, the symptoms disappeared completely.
Conclusion: Eosinophilic colitis is a rare adverse effect of clozapine. It is only possible to diagnose this using endoscopy and biopsy, so that the complaint is often not recognised. The exact pathophysiology underlying this eosinophilic colitis is not known.