Dithranol or anthralin has a slower onset of action in controlling psoriasis, typically several weeks, compared to glucocorticoid steroids, but is without the potential for rebound reaction on withdrawal. it cannot be used on the face or genitalia. there is some tentative evidence that anthralin maybe useful alopecia areata.it temporarily stains the skin a yellowy-brown and permanently stains clothing fabrics and other materials such as ceramic sinks. it may cause a local burning sensation and irritation.