Allopurinol and Febuxostat Hypersensitivity in a Patient with Young Onset Gout: A Case Report.

Gout is the most common inflammatory arthritis among Filipinos, characterized by hyperuricemia leading to monosodium urate crystal deposition and an ensuing inflammatory response. Though typically a disorder of middleaged and older adults, tophaceous gout presenting before the age of 30 is rare and suggests aggressive disease progression. Allopurinol, a first-line urate-lowering therapy, is generally effective but may cause rare, potentially life-threatening adverse reactions such as allopurinol hypersensitivity syndrome (AHS). Febuxostat, a non-purine xanthine oxidase inhibitor, is an alternative for patients intolerant to allopurinol. Although hypersensitivity reactions to febuxostat are extremely rare, isolated case reports document their occurrence in both patients with prior AHS and in allopurinol-naïve individuals. Hypersensitivity to both agents is exceedingly uncommon and presents a major therapeutic challenge. In such cases, febuxostat desensitization, conducted in collaboration with allergy specialists, may permit a viable solution to safely reintroduce urate-lowering therapy and prevent further disease progression. This case report describes a patient with young-onset, tophaceous gout who developed severe hypersensitivity reactions to both allopurinol and febuxostat - an unusual and challenging therapeutic dilemma. The case highlights the need for individualized management strategies, including the consideration of drug desensitization, in patients with limited urate-lowering options.