A Double-Edged Puzzle: Diagnostic Challenges in Herpes-Triggered Erythema Multiforme and Methotrexate Oral Toxicity.

A 56-year-old female on long-term methotrexate presented with painful oral ulcerations diagnosed as erythema multiforme. Despite continued methotrexate use, lesions resolved with acyclovir and corticosteroids, confirming herpes simplex virus-associated erythema multiforme. This case highlights the importance of therapeutic response in distinguishing viral triggers from drug-induced causes for accurate management.