This case report documents a rare occurrence of pellagra in a chronic alcoholic individual, characterized by a pruritic rash and gastrointestinal symptoms. The patient, a Caucasian male in his 60s, with a history of alcohol use disorder, presented with worsening skin lesions and non-bloody diarrhea. Laboratory findings revealed significant deficiencies in niacin and related metabolites, confirming the diagnosis. Prompt initiation of niacin supplementation, dietary adjustments, and supportive care led to notable improvements. This case shows the critical importance of recognizing pellagra in chronic alcoholism, emphasizing the triad of symptoms - rash, diarrhea, and malnutrition - as key diagnostic markers. Early intervention holds the potential to significantly enhance the patient's well-being and prevent disease progression.