Coal tar . Coal tar is one of the oldest treatments for psoriasis, and is available both with and without prescription. However, its most effective use is recommended and supervised by a dermatologist, sometimes in combination with phototherapy. Although coal tar is an old standby treatment it is still regarded as effective for mild for moderate plaque psoriasis. It is a complex substance and its anti-psoriasis constituents have not been identified with certainty.
Side effects are minimal.
Retinoids are vitamin A derivatives also used in treatment of acne, sun-damaged skin and other dermatologic conditions. Tazarotene is a synthetic retinoid recently introduced for treatment of mild to moderate plaque psoriasis, and psoriasis of the scalp and nails. It is applied as a gel, in a strength recommended by the dermatologist. Retinoids normalize DNA activity in skin cells, thus decreasing the cell proliferation of psoriasis and normalizing abnormal cellular growth in the hair follicle that is a contributing cause of acne. Local skin irritation is the most common side effect, which may be reduced by use of a topical steroid.