Anthralin, marketed in the USA under the brand names Drithocreme, Psoriatec, Dritho-Scalp and Zithranol-RR, is a synthetic form of the naturally occurring substance cachrysarobin, which comes from the araroba tree of South America. It is used for the topical treatment of psoriasis. Anthralin preparations come in a range of concentrations formulated as creams, ointments and scalp lotion. The lower concentration formulations are available over-the-counter. The active ingredient works by slowing down the growth of skin cells, which is accelerated in psoriasis. Anthralin also has anti-inflammatory properties. Anthralin has a good safety profile, however it carries an FDA pregnancy category rating of C, which means its affect on a human fetus is not know. Similarly, its affect on newborns who are nursing is not known, therefore it is not routinely recommended for use in pregnant or nursing mothers. One of the drawbacks of Anthraline is that it may stain your hair, fingernails, skin, clothing, bed linens, or bathtub or shower. Any staining on your skin will wear off once you stop using the medication — the stains can take several weeks to disappear.