BLU-U BLUE LIGHT PHOTODYNAMIC THERAPY is a special blue light that is used to treat acne, actinic keratoses of the face or scalp as well as sun-damaged skin. This procedure is non-invasive and pain free, with full-face and neck treatment. The Blu-U acne light works with all skin types and acts by killing acne-causing bacteria, overactive oil glands, premalignant skin cells and pre-cancers.