Pancytopenia and stomatitis induced by low-dose methotrexate use

Rheumatoid arthritis (RA) is the most common systemic, autoimmune, and chronic inflammatory disease causing symmetrical arthritis in joints. To prevent its progression, disease-modifying drugs are used. Among these, methotrexate (MTX) is the first choice drug. MTX is an agent which blocks deoxyribonucleic acid synthesis by competitively inhibiting folic acid metabolism. During treatment, rare but severe side effects such as pancytopenia, hepatotoxicity, mucositis, and pulmonary toxicity can be seen. In this case, a 76-year-old woman diagnosed with RA developed stomatitis and severe pancytopenia after treatment with low-dose MTX is reported.