ABSTRACT
Light-emitting diodes (LED) can emit lights of different wavelengths, including blue light, yellow light, red light and infrared light. LED has been widely used in dermatology due to its high safety, maneuverability, color purity and low energy. For example, blue light is mostly applied to acne treatment, yellow light is usually used in melasma treatment, red light can be used in treatment of androgenetic alopecia, and infrared light has the function of promoting skin repair. Combination of multi-band lights tends to be applied in clinical practice. For example, the red light and blue light combination, red light and yellow light combination, as well as yellow light and infrared light combination are effective for acne treatment, repair after laser treatment, and skin rejuvenation respectively.