A: Blue light kills the acne-causing bacteria known as Propionibacterium acnes, or P acnes, which can cause inflammation. P acnes is sensitive to blue light. Using the blue light, eliminates the bacteria found in the oil glands in the skin. The added presence of infrared light (heat) in the home device causes the oil glands to shrink in size. The result is less oil in the skin and less bacteria, leading to the resolution of acne in the treated areas.