Topical steroids are usually prescribed for selected purposes for limited periods of time, and are frequently used in combination with other agents. Regular skin care with moisturizing and lubricating agents prevents skin dryness during and between periods of psoriasis therapy. Excessive skin dryness can be a trigger for new psoriasis lesions. Systemic Agents Systemic agents are given internally, orally or by injection, to influence the course of psoriasis. However, they also have a variety of other systemic effects and must be used under close supervision and monitoring by a dermatologist.
Systemic agents are often combined with topical agents for better clearing of lesions.
Methotrexate was first introduced as an anti-cancer agent and has since been adapted to a number of other therapies, including treatment of psoriasis. Methotrexate is in the class of drugs called antimetabolites that is, they act therapeutically by influencing the metabolism of target cells. It is especially useful in treatment of pustular psoriasis and psoriatic arthritis . Methotrexate is a potent drug with multiple effects on tissues. Side effects may involve the gastrointestinal system, liver, lungs, and blood.