Methotrexate side-effects.

Methotrexate is by far the most widely used cytotoxic drug in psoriasis. Treatment requires normal kidney, liver and bone-marrow function, and pregnancy and alcohol abuse are absolute contraindications. Serious toxic reactions are recognized, but can be avoided if the drug is used correctly. The most important side-effects are haematopoietic and hepatotoxic. It is well established that long-term methotrexate can induce liver damage which, in a number of patients, may lead to fibrosis or cirrhosis. Recent studies have, however, documented that the methotrexate-induced liver cirrhosis is not aggressive. Interaction can occur with a number of drugs; serious problems in particular may arise with concomitant use of sulphonamides and salicylates. The recommended guidelines for methotrexate use in psoriasis should be followed and patients given clear instructions.