A number of topical therapies are available for psoriasis and are most often used for localized areas. The most common topical therapy for psoriasis is superpotent topical steroids (e.g clobetasol, augmented betamethasone, halobetasol). Topical steroids are available in a variety of vehicles such as creams, lotions, ointments, sprays, gels and foams. Topical steroids work by reducing inflammation and restore the normal thickness of the skin. Sometimes Saran wrap is used to occlude topical steroids in order to enhance their penetration into thick plaques. Local side effects limit long-term continuous use of potent topical steroids. Topical vitamin D preparations such as Dovonex and calcitriene are often effective in maintenance therapy of psoriasis. Some therapies combine both topical steroids and topical vitamin D into one vehicle (e.g Taclonex and Enstillar). Topical retinoids such as Tazorac may also be of effective treatment for psoriasis but these are sometimes irritating to the skin.   Topical calcineurin inhibitors such as Protopic and Elidel are non-steroidal and valuable for use on the face, axilla, groin, and genital region.   Other nonsteroidal options include ammonium lactate lotion, salicylic acid, and urea to soften the plaques. Classically, coal tar has been used in various preparations but has fallen out of favor due to the fact that it can stain clothing and is messy to use.