Melanin is a substance the present Naturally in our skin and it is responsible for the coloration of the skin, thus skin bleaching is all about stopping the formation of this substance and also removing the existing melanin in the spot or discolored area of the skin, scientists related an enzyme produced in the body called tyrosinase to the activation of melanin production in the skin, so in order to stop melanin production in a part of the skin, this enzyme must be deactivated.
One of the most actively used ingredients in skin bleaching is called hydroquinone, and it is the only recognized skin bleaching agent by the USFDA recently, however there are other ingredients used in skin bleaching such as kojic acid, and azelaic acid, these ingredients are termed as brightener.
These ingredients are what is usually found in skin bleaching formulas and research are being carried out to find more skin bleaching ingredients that are effective and not harmful.
For removing the existing skin coloration, two chemicals are being mainly used to exfoliate the skin first and replace the old skin with new skin, these chemicals are called AHAs and tretinoin , however you must consult your doctor before attempting to use any skin bleaching formula because some of them may irritate your skin.
Your doctor will be able to guide you to a suitable brand for your skin type that will be effective in removing any existing coloration and also prevent any future coloration, you should also stop immediately any skin bleaching product that irritates your skin.