From Treatment to Tragedy: Severe Methotrexate Toxicity With Mucocutaneous Ulcers, Myelosuppression, and Nephropathy

Methotrexate (MTX) is a well-established drug for the use of various neoplastic disorders. Recently, it has been widely used as a disease-modifying antirheumatic drug (DMARD) in low doses, mainly for rheumatoid arthritis (RA) and psoriasis. The drug is known to cause renal damage as well as be excreted via the kidneys, thus causing a higher incidence of adverse effects in patients with impaired renal function. The side effects of MTX toxicity range from mucocutaneous ulcers to nephrotoxicity and bone marrow depression, all of which are seen in this case. Here, we report an elderly male in his late 60s who was prescribed MTX 15 mg once a week along with folic acid 5 mg for RA by a general practitioner. Despite being prescribed once weekly, he continued to take MTX daily without following up with a physician for a span of five months. Following this, he presented to the medicine outpatient department with odynophagia due to oral ulcers for 10 days. He was diagnosed with MTX toxicity, causing nephropathy, myelosuppression, and mucocutaneous ulcerations. He was treated with injectable leucovorin 100 mg thrice a day until the toxicity subsided, leading to his eventual recovery.