What is a known toxicity associated with methotrexate?

Methotrexate is an antimetabolite and immunosuppressant commonly used to treat certain cancers, autoimmune diseases, and ectopic pregnancies. One of its known toxicities is pulmonary fibrosis, which refers to the scarring of lung tissue that can lead to breathing difficulties and reduced lung function.

The development of pulmonary fibrosis as a side effect of methotrexate is significant because it can occur even in patients who have been on the medication for a long time. Clinicians monitor for symptoms such as coughing, shortness of breath, and decreased exercise tolerance when a patient is undergoing treatment with methotrexate.

While other options like kidney failure can occur due to methotrexate at high doses, it is not as prominently associated with the drug's profile as a well-known toxicity compared to pulmonary fibrosis. Similarly, heart failure and skin cancer are not directly linked to methotrexate therapy in the same way. Thus, pulmonary fibrosis stands out as a critical and recognizable complication in patients treated with this medication.