IPL can cause localized damage by selectively heating dark target matter, melanin, in the area that causes hair growth, the follicle, while not heating the rest of the skin. Light is absorbed by dark objects, so IPL energy can be absorbed by dark material in the skin, but with much more speed and intensity. This dark target matter, or chromophore, can be naturally-occurring or artificially introduced.
Melanin is considered the primary chromophore for all hair removal IPL currently on the market. Melanin occurs naturally in the skin, and gives skin and hair their color. There are two types of melanin in hair. Eumelanin gives hair brown or black color, while pheomelanin gives hair blonde or red color. Because of the selective absorption of photons of IPL light, only black or brown hair can be removed. IPL works best with dark coarse hair. Light skin and dark hair are an ideal combination, being most effective and producing the best results, but new IPL are now able to target dark black hair with some success in patients with dark skin.
IPL hair removal has become popular because of its speed and efficacy, although some of the efficacy is dependent upon the skill and experience of the IPL operator, and the choice and availability of different IPL technologies used for the procedure. Some will need touch-up treatments, especially on large areas, after the initial set of 3-8 treatments. It has also been noted that some people are "non-responders" – this occurs when the incorrect device is being used, the device parameters are too low or the patient is simply not a good candidate for treatment