Methotrexate Toxicity Management in Polymyalgia Rheumatica: A Case Report

Methotrexate (MTX) is an anti-folate drug with anti-inflammatory and anti-proliferative properties. Low-dose methotrexate (10-25 mg/week) is widely recognized as a safe and effective treatment for various autoimmune disorders. While toxicity from low dose methotrexate is uncommon it can lead to severe complications like pancytopenia. We present a case of a 68-year-old male with a history of steroid-resistant Polymyalgia Rheumatica on methotrexate (20 mg weekly) and prednisone. He presented to the emergency room with oral mucosal lesions and reduced oral intake. Upon evaluation, he was found to have pancytopenia and transaminitis, raising concern for methotrexate toxicity. Treatment included folinic acid rescue therapy and filgrastim. This case highlights the importance of promptly identifying signs of methotrexate toxicity and regularly monitoring patients for adverse effects by healthcare providers.