Beneath the surface of SkinZinc system

The product: Unless your radio dial is stuck on NPR, you've probably heard a few pitches for SkinZinc, a "revolutionary" treatment for psoriasis. The radio ads -- featuring glowing testimonials from alleged customers -- have clearly made an effect. "Patients ask about SkinZinc very frequently," says Dr. Kenneth Gordon, assistant professor of dermatology at Northwestern University and a medical board member of the National Psoriasis Foundation. "I know I have many patients who have gone out and bought it."

Any real breakthrough in psoriasis treatment would certainly be welcome news for the more than 5 million Americans with the skin condition, which is marked by scaly, itchy, occasionally painful rashes. Prescription medications -- including steroid creams that ease inflammation -- are far from perfect. "We can control psoriasis, but we can't cure it," says Dr. Steven Feldman, professor of dermatology at Wake Forest University. "People want something magical that will work without side effects."

The SkinZinc system -- sold at major drugstores and over the Internet -- combines two products: SkinZinc spray and SkinCylic cream. The active ingredient in the spray is a 0.25% solution of zinc pyrithione, the same active ingredient found in Head & Shoulders dandruff shampoo. SkinCylic cream contains 2% salicylic acid, a common ingredient in both prescription and over-the-counter psoriasis treatments. The Walgreen's website sells 4 ounces each of the spray and the cream for about $40.

The claims: Bernard Willimann, executive vice president for Preval Health, the Maine-based company behind SkinZinc, says that the system is the bestselling over-the-counter treatment for psoriasis in the U.S. and Canada. "Some people try it without success, but a lot of people are very loyal to it," he says. "Some of the letters and pictures we get are amazing."

In one radio spot, an unidentified customer calls it "the closest thing to a medical miracle." Ads in national magazines claim that the SkinZinc spray "goes on like water to help eliminate painful, stubborn symptoms, including itching, scaling, flaking, and redness."

Ads and product labels state that SkinZinc is effective for dandruff and seborrheic dermatitis (a relatively mild rash of the face, scalp or trunk) as well as psoriasis.

Bottom line: Skin products containing zinc have "been around forever," Gordon says, but there's no evidence that they help treat psoriasis. He suspects that a zinc spray might slightly ease inflammation and that it might be a bit more helpful for seborrheic dermatitis than for psoriasis.