Near fatal drug interactions with methotrexate given for psoriasis

Abstract

Methotrexate and trimethoprim are folate antagonists which, given together, may produce a synergistic effect on folate metabolism. Non-steroidal anti-inflammatory drugs may also interact with methotrexate. We describe a patient who developed necrotic skin ulceration and pancytopenia after concurrent administration of methotrexate, trimethoprim, and naproxen. © 1987, British Medical Journal Publishing Group. All rights reserved.