Pellagra in Contemporary Clinical Practice (2000–2023): A Systematic Review

Pellagra's clinical presentation, etiological factors, and treatment in the early 21st century remain underexplored. This study aimed to update the understanding of pellagra's clinical and etiological aspects with a reappraisal of its treatment and prevention. We searched PubMed and Scopus up to January 9, 2023, to identify relevant studies. The reference lists of all included articles were also carefully screened to identify any additional studies. We included case reports, case series, and case-control studies documenting confirmed cases of pellagra between 2000 and 2023. The review protocol was registered with PROSPERO (CRD42022381416). The search identified 918 studies, of which 133 met the inclusion criteria, comprising 1212 pellagra cases. Cutaneous manifestations were the most common (98.63%), followed by gastrointestinal (59.4%) and neurological (54.2%) signs. Complete symptom resolution occurred on average within 27.42 days of vitamin B3 supplementation. Dietary deficiency remained the predominant cause of pellagra (85%), and it was particularly common in populations affected by food insecurity or humanitarian crises, accounting for 93% of cases. Alcohol misuse was reported in 9.6% of cases. Isoniazid was the leading drug-related cause (14.3%). Other contributing factors included gastrointestinal disorders and prior surgeries associated with malabsorption. These findings indicate an evolving etiological pattern in pellagra: dietary deficiency remains the primary driver, yet medication-induced and malabsorption-related cases are increasingly reported. Targeted niacin supplementation strategies for high-risk populations may improve outcomes and enable more efficient, lower-dose therapeutic approaches once underlying causes are addressed.