[Serious complications during treatment with methotrexate: also in chronic low-dosage use].

Methotrexate is a frequently prescribed drug and is considered to be safe at a low dosage. However, serious complications may occur during treatment. In this article we describe a 78-year-old male who used low-dose methotrexate for psoriatic arthritis. He died of multi-organ failure caused by sepsis and methotrexate intoxication as a result of deteriorating renal function. The second patient was a 56-year-old male who used low-dose methotrexate for rheumatoid arthritis. This patient developed pancytopenia and methotrexate pneumonitis during treatment with methotrexate. We recommend the frequent monitoring of blood count and renal and liver function tests to detect early deterioration. Furthermore, doctors should be aware of conditions and factors predisposing to methotrexate intoxication, such as impaired kidney function and co-medication. If methotrexate intoxication is suspected, intravenous folinic acid should be administered immediately.