Severe psoriasis requires systemic treatment, and the main active agents are cyclosporin A, methotrexate, and retinoids.

  • Cyclosporin A (CsA) is an immunosuppressant drug, discovered at the end of the 1970s, and is very effective when used at a dose of 3–5 mg/kg/day. Once the patient is in clinical remission, generally within two months of beginning treatment, it is possible to switch to a maintenance dose, or to stop treatment altogether. The duration of treatment cycles should not exceed six months; however, these can be repeated if necessary.
  • Methotrexate (MTX) is another immunosuppressant drug, taken orally or administered intramuscularly or intravenously. Most patients respond to doses of 7.5-15 mg/week. The drug is toxic for the liver and bone marrow, especially at high doses.
  • Acitretin, a vitamin A derivative, is an effective treatment for pustular and erythrodermic psoriasis. It is taken orally at an initial daily dose of 10-20 mg, which can be increased up to 50 mg if necessary. This drug has substituted etretinate, because it is metabolised more rapidly. Like all retinoids, it has a number of contraindications, particularly in women of childbearing age, as it is teratogenic. Patients should abstain from drinking alcohol during treatment; known side effects are dryness of the lips, nose and eyes.