Figure 5.

Illustration of acne treatment with red and blue light.

Red and blue light when used in combination have synergistic effects in treatment of acne. P. acnes synthesizes and stores a large amount of porphyrins. Once the porphyrin is exposed to visible light (specifically blue light) it becomes chemically active and transfers to an excited state, resulting in formation of reactive free radicals and singlet oxygen which in turn causes membrane damage in P. acnes ^49,53. Red light is proposed to exert its effects through reducing the inflammatory process ^51,54.