Acute cutaneous adverse effects of methotrexate: A case report highlighting therapeutic challenges

Methotrexate (MTX) is a commonly used antimetabolite for managing various autoimmune disorders and cancers. While it is generally well-tolerated at low doses, certain factors may predispose patients to significant toxicity. Here we present a case of 49-year-old male with advanced buccal mucosa squamous cell carcinoma who developed acute severe cutaneous toxicity following low dose of intravenous MTX therapy. After receiving two weekly doses, the patient experienced grade 4 oral mucositis and multiple erythematous plaques. This case highlights the importance of early recognition and prompt management of MTX toxicity, even at low doses, particularly in patients with risk factors such as prior antibiotic use and low serum albumin levels.