The Hidden Perils of Allopurinol: A Systematic Review of Allopurinol-Induced DRESS (Drug Reaction With Eosinophilia and Systemic Symptoms) Syndrome

Drug hypersensitivity reactions are a clinically significant and potentially preventable cause of hospital admission, treatment interruption, and drug-related mortality worldwide. Within severe cutaneous adverse reactions (SCARs), a group that includes Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN), acute generalized exanthematous pustulosis (AGEP), and drug reaction with eosinophilia and systemic symptoms (DRESS), DRESS stands out because of its delayed onset, multi-organ involvement, and frequent diagnostic uncertainty. Allopurinol is a commonly prescribed medication for hyperuricemia, but in rare cases, it can trigger DRESS. This systematic review was conducted to comprehensively summarize the demographic characteristics, clinical manifestations, diagnostic features, management strategies, and outcomes of reported cases of allopurinol-induced DRESS syndrome. Available case reports and case series were analyzed to consolidate patient characteristics, patterns of organ involvement, treatment approaches, and clinical outcomes. The findings indicate that allopurinol-induced DRESS most often presents with cutaneous manifestations and systemic involvement, most commonly affecting the liver and kidneys, and is associated with considerable morbidity and mortality despite treatment. These results emphasize the importance of early recognition, prompt drug discontinuation, and cautious prescribing of allopurinol, particularly in high-risk populations.