Methotrexate-induced Severe Pancytopenia in a Patient with Rheumatoid Arthritis: A Case Report and Review of Literature.

Toxicity associated with low doses of methotrexate (MTX) is low, but it may be fatal. Bone marrow suppression and mucositis are among the common side effects of low dose MTX toxicity. Different risk factors have been reported for toxicities associated with low doses of MTX, including accidental use of higher doses, renal dysfunction, hypoalbuminemia, and polypharmacy. In this paper, we present a female patient who had mistakenly used 7.5 mg of MTX daily instead of the same dose of MTX on Thursday and Friday. She was presented with mucositis and diarrhea to the emergency department. Moreover, we searched the databases Scopus and PubMed for available studies and case reports on toxicities associated with MTX dosing errors. The most frequently observed toxicities included gastrointestinal lesions, nausea, vomiting, skin lesions, and bone marrow suppression. Leucovorin, hydration, and urine alkalinization were among the most frequently used treatments. Finally, we summarize the data on the toxicities of low doses of MTX in different diseases.