Instead of directing you to sale items, this blue light can help ward off skin cancer if you have actinic keratoses, rough patches of skin caused by excessive sun exposure.

An innovative two-step process helps treat and reduce the number of precancers as well as reduce the number of full-fledged skin cancers. During the first step, a UI Hospitals and Clinics dermatologist applies a colorless liquid, called aminolevulinic acid, to your lesions. In the next step, you are exposed to a non-laser fluorescent light—the blue light—which activates the acid in the solution and destroys the lesions.

“Photodynamic therapy is a helpful alternative method to treat actinic keratosis,“ says Vincent Liu, MD, UI Hospitals and Clinics dermatologist. “It can treat large areas of skin with little discomfort and many people are good candidates for the therapy.”

Those most at risk are at least 40 years old, and are fair skinned with blue, green, or hazel eyes.