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Methotrexate and trimethoprim — GPhC CRA MCQ

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ModerateMusculoskeletal TherapeuticsMethotrexate and trimethoprimGPhC CRA

A patient taking weekly methotrexate is prescribed trimethoprim for UTI. What is the most important interaction to flag?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: BIncreased risk of bone marrow suppression

Trimethoprim can add antifolate effects and increase methotrexate toxicity risk. In this vignette, "Increased risk of bone marrow suppression" is the safest single best answer. The other options are less appropriate because they miss the key clinical risk, conflict with UK medicines guidance, or delay needed review.

Reference: BNF; NICE CKS