Isoniazid-induced pellagra.

Pellagra is characterized by dermatitis, diarrhea, dementia and eventually death occurring as a result of niacin or its precursor tryptophan deficiency. Although pellagra is a well-known complication of isoniazid (INH) therapy, the clinical diagnosis may be missed or delayed that may cause life-threatening consequences. Due to the diversity of pellagra-related signs and symptoms, the diagnosis can be made with an appropriate index of suspicion. We report a 7-year-old boy presenting with INH-induced pellagra that resolved after the administration of the niacin therapy.