Clozapine, renowned for its efficacy in treatment-resistant schizophrenia, is associated with rare yet potentially severe side effects, including hematological disorders, myocarditis, seizures and gastrointestinal obstruction. Dermatological adverse effects, though less serious, can profoundly impact patients' quality of life. We present the first reported case of cholinergic urticaria induced by clozapine, in a 25-year-old male with treatment-resistant schizophrenia. Four months into clozapine therapy, the patient developed intensely pruritic erythematous lesions triggered by sweating, significantly impairing his daily activities. Despite attempts at management, including dose reduction and antihistamine therapy, the urticaria persisted. However, a favorable outcome was achieved upon switching to quetiapine. This case underscores the importance of recognizing and managing treatment-related adverse effects, even when they arise late in treatment, and highlights the need for individualized therapeutic approaches.We discuss potential mechanisms underlying clozapine-induced cholinergic urticaria and emphasize the significance of patient-centered care in optimizing treatment outcomes in schizophrenia.
Keywords: case report; cholinergic urticarial; clozapine.
Itchy rash from sweating with clozapine Despite its undisputed efficacy, clozapine has attracted a great deal of attention for its rare but potentially serious side effects, such as hematological disorders (in particular, low white blood cell counts), seizures and inflammation of the heart muscle. Other effects, notably cutaneous, have also been reported, and although they are not serious, they can have a considerable impact on the patient’s quality of life. Such is the case of our patient who became allergic to his own sweat while taking clozapine. To our knowledge, this is the first case described in the literature. The patient was a 25-year-old man suffering from resistant schizophrenia, i.e. who had failed to respond to successive use of two different antipsychotics. Four months after starting treatment with clozapine, he developed a generalized cutaneous eruption characterized by intensely pruritic erythematous punctiform lesions which appeared with each episode of perspiration. The lesions considerably disrupted the patient’s daily activities, making it necessary to refrain from physical effort and avoid exposure to heat. Despite attempts to manage symptoms, by treatment with antihistamines and clozapine dose reduction, the urticaria persisted. However, a favorable and durable outcome was observed after switching to quetiapine rather than olanzapine. This case highlights the importance of recognizing and managing treatment-related undesirable side effects, even if they appear late in the course of treatment, and of not neglecting their impact on the patient’s daily life. In this report, we have also tried to outline the hypothetical mechanisms that could explain this unusual side effect. This case encourages clinicians to always seek the optimal antipsychotic for their patients, even after several therapeutic failures and/or episodes of intolerance. Trial and error can lead to more effective, personalized treatment.
© The Author(s), 2024.