Allopurinol-induced dress syndrome in a case of renal insufficiency

Introduction: Allopurinol, a xanthine oxidase inhibitor, is widely prescribed in cases of gout and hyperuricosuria. Notably, allopurinol is not recommended in the case of asymptomatic hyperuricemia. Despite its efficacy, it carries the risk of rare but severe hypersensitivity reactions such as Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome which is characterised by fever, rash, facial oedema, eosinophilia, and multiorgan involvement, typically emerging 2–8 weeks after drug initiation. Case Presentation: A 63-year-old female with a history of hypertension and chronic kidney disease presented to Dermatology OPD with a 10-day history of generalised morbilliform rash, pruritus, and facial oedema. These symptoms developed 1 month after initiating allopurinol for asymptomatic hyperuricemia. On examination, skin lesions were present on the trunk and extremities as morbilliform eruptions along with desquamation of skin over face and back, and systemic manifestations. Laboratory results revealed leukocytosis, marked eosinophilia, elevated pancreatic enzymes impaired hepatic and renal function tests. A diagnosis of allopurinol-induced DRESS syndrome was made. Allopurinol was discontinued, and the patient was treated with systemic corticosteroids and supportive care. Clinical and biochemical parameters improved over 21 days, and corticosteroids were tapered over 2 months. The causality assessment using the WHO scale classified the reaction as “Probable/Likely.” Conclusion: This case highlights the development of DRESS syndrome following allopurinol ingestion in a 63-year-old female with renal insufficiency. Our case underscores the need for heightened awareness of drug toxicity reactions in geriatric patients receiving allopurinol. Allopurinol-induced DRESS syndrome carries a high risk of mortality, so caution is essential while prescribing this drug as well as careful consideration of the co-morbidities and associated risk factors.