What is known and objective: Clozapine is the most effective medication used in treatment-resistant schizophrenia; however, it has some serious side effects, including agranulocytosis, myocarditis, cardiomyopathy, and hyperglycemia, and the frequency of drug eruption with clozapine is approximately 0.5%.
 According to a review by Manu et al. in 2018, there were 259 reports of rechallenge after discontinuation of clozapine due to its side effects. However, there is no report on rechallenge with clozapine after drug eruption.
 Here, we report a case that was successfully rechallenged with clozapine after suspicion of drug eruption.
 Case summary: A 30-year-old Japanese male with treatment-resistant schizophrenia developed a rash while consuming 350 mg/day of clozapine after 31 days of taking the drug. A 1-cm sized erythema with pruritus was observed on the trunk. The patient immediately discontinued clozapine after the emergence of the erythema, because drug eruption was suspected. After stopping clozapine, the erythema healed quickly. After five years, it was decided to rechallenge with clozapine, because other treatments including electroconvulsive therapy were not effective.
 We consulted a dermatologist before starting clozapine and conducted some examinations, such as patch test and drug-induced lymphocyte stimulation test. After confirming that the examination was negative, we started an oral test of clozapine. In the oral test, the dose was carefully increased every three days to 1.2 mg, 2.5 mg, 6.25 mg, and 12.5 mg to confirm that there was no appearance of rash. The consumption of other antipsychotic drugs was not reduced when taking clozapine in small amounts.
 What is new and conclusion: It could be possible to rechallenge with clozapine after drug eruption has been suspected, following consultation with dermatologists and conducting sufficient examinations for drug eruption.
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