It's a new era for patients covered in the itchy, scaly skin disease psoriasis. After years with few good treatments, doctors finally have a handful of therapies that promise to help control the incurable condition with fewer bad side effects.

　　What changed? Scientists learned that psoriasis isn't just a skin-deep disorder but a dysfunction of the immune system, so the new therapies target the real culprit.

　　"Five to six years ago, I was telling my patients it was the wasteland," says Dr Craig Leonardi of St Louis University Medical School, who participated in studies of the new treatments. "Now there's this huge explosion of amazing drugs coming forward."

　　The new options don't help everyone, cautions Dr Michael Tharp, dermatology chief at Chicago's Rush University Medical Center. And they're very expensive, costing US,000 a year or more.

　　But, "it's a great first step," Tharp says. "Now we've got very directed molecules and knowswheresthey work and how they work. ... I hope it is just the beginning."

　　Two unique psoriasis shots, Amevive and Raptiva, recently won US Food and Drug Administration approval. Two drugs already sold to treat other conditions - Enbrel and Remicade - are used against psoriasis, too. A list of other potential treatments is under study.

　　The four newest options haven't yet been compared to each other, but because each works somewhat differently, specialists expect hard-to-treat patients to find some relief among the bunch.Some 4.5 million Americans have psoriasis. Of those, 1.5 million suffer moderate to severe symptoms - their skin covered in red or white scaly patches that burn and itch. It's triggered when certain immune system cells, called memory effector T cells, run amok, causing skin cells to multiply faster than normal and become inflamed.

　　It can be life-altering.

　　"I wouldn't wear anything but long-legged pants and long-sleeved shirts because I got so tired of people asking me questions," says Lyle Newcomb, 60, who tried every treatment without success.Then Newcomb entered a study of Raptiva. "I had never been clear of psoriasis in my life, but I was totally clear in three weeks," and, two years later, weekly shots keep symptoms at bay.Ointments and light therapy - ultraviolet beams, sometimes with light-sensitizing drugs, a few times a week - are effective for milder psoriasis.

　　Until now, patients had two powerful options, each with serious side effects. The immune suppressor cyclosporine, commonly used to prevent rejection of transplanted organs, can destroy kidneys. Inflammation-suppressing methotrexate, also used for cancer and rheumatoid arthritis, can cause liver damage.The new biologically engineered treatments promise more targeted therapy without those risks.

　　Specialists call the four new treatments largely safe but acknowledge that even mildly tinkering with the immune system for years might spur infections or cancer.