Major
Diclofenac × Methotrexate
Non-steroidal anti-inflammatory drugs (NSAIDs)×Antimetabolites, folic acid analogues
Mechanism
Diclofenac, like other NSAIDs, reduces methotrexate renal clearance. With high-dose methotrexate – fatal myelosuppression and nephrotoxicity. With low-dose methotrexate – higher risk of cytopenia and liver injury.
Symptoms
Same as with ibuprofen: mucositis, cytopenia, rising creatinine and transaminases.
Management
Same approach as methotrexate+ibuprofen. If a rheumatoid arthritis patient needs an NSAID, prefer paracetamol or a short ibuprofen course with lab monitoring.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.