Photodynamic therapy requires three basic elements to work: A photosensitizer: Acne light treatment is based on the fact that P. acnes bacteria produce porphyrinsas metabolic products. These porphyrins act as internal photosensitisers inside the pilosebaceousfollicle and are activated by visible light, creating a photochemical reaction which eradicates bacteria. The external application of a photosensitizing substance [...]