Methotrexate use in psoriasis and psoriatic arthritis.

Methotrexate is an extremely effective drug in the treatment of psoriasis and psoriatic arthritis. In addition, it possesses a very high benefit-to-toxicity ratio compared with other therapies and immunosuppressive agents used in these disorders. Fortunately, most adverse events related to methotrexate are mild, but serious and life-threatening reactions, particularly liver toxicity, may occur. Careful monitoring is essential to prevent most undesirable side effects.