ABSTRACT

Oral mucositis as a result of methotrexate intoxication due to erroneous dosing regimen

Methotrexate (MTX), a folic acid antagonist and analogue, is widely used in both neoplastic and chronic inflammatory diseases. Side effects of the drug and their severity depend on the dose used, so they are significantly more frequent when the drug is used for oncological indications. An infrequent but life-threatening complication is drug overdose associated with misinterpretation of medical recommendations. We present a case of a 68-year-old female patient consulted due to extensive erosive changes in the oral cavity accompanied by increased body temperature. The patient had a previous history of arthritis, arterial hypertension, hyperuricemia, gastroesophageal reflux, type 2 diabetes and hypercholesterolaemia. Fifteen days before, she completed hospitalization in the rheumatology department, during which, due to arthritis, she was recommended MTX therapy at a dose of 15 mg per week. A detailed medical history allowed for the diagnosis of ulcerative stomatitis, which developed as a result of improper daily intake of the drug at a dose of 15 mg/day for a period of 11 days. Few cases of ulcerative stomatitis induced by an inadvertent MTX overdose have been reported in the literature, and the most common scenario was taking the drug daily instead of the recommended weekly intake – as in the presented case. The analysis of medications taken by the patient should be a mandatory diagnostic step in the case of a patient presenting with erosive stomatitis associated with elevated body temperature, and a thorough medical history often allows for diagnosis.