Why should patients taking methotrexate avoid aspirin (ASA) and NSAIDs?

The correct choice is that aspirin and NSAIDs can enhance the effects of methotrexate by increasing serum concentration. When patients are treated with methotrexate, a medication often used for conditions like rheumatoid arthritis and certain cancers, careful monitoring of drug interactions is crucial.

Aspirin and NSAIDs can inhibit renal function and affect the elimination pathway of methotrexate. This interaction leads to an increased serum concentration of methotrexate, which can heighten the risk of toxicity, as the drug's side effects could be exacerbated. Higher levels of methotrexate may lead to more severe adverse effects, such as bone marrow suppression, liver toxicity, and increased incidence of gastrointestinal issues.

While options relating to bleeding, decreased absorption, or gastrointestinal side effects could also present concerns, the primary reason to avoid combining methotrexate with aspirin or NSAIDs is the potential for increasing methotrexate serum levels and the risk of subsequent toxicity.