[Methotrexate in dermatology: current aspects].

The prescription of methotrexate (MTX) in dermatology is nowadays restricted for two main reasons: the toxicity of the drug and the availability of less toxic treatments (phototherapy and etretinate) in its main indication: psoriasis. However, MTX remains very useful in severe psoriasis, to some extent, in various dermatological diseases, such as dermatomyositis. A perfect knowledge of its adverse effects (slight on the gastrointestinal tract and bone marrow, much more serious on the liver and lung) allows a reasonable use of the drug but cannot avoid the unpredictable hypersensitivity pneumopathy.