Abstract
Niacin (Vitamin B3) plays a crucial role as a vitamin in cellular energy production, metabolism, and DNA repair. A severe deficiency of this vitamin can lead to pellagra, which is characterized by dermatitis, dementia, diarrhoea and eventually death if untreated. A 68-year-old woman with a poor socioeconomic background presented with photosensitive dermatitis, fever, abdominal pain, and diarrhoea. Her urine changed to port wine colour following sun exposure. Porphyria cutanea tarda was excluded in the absence of demonstrable urine spectrophotometry. A diagnosis of pellagra was made, and timely management led to a complete cure. Proper diagnosis and effective treatment of pellagra are imperative as this condition can be life-threatening if left untreated.