I am reading a book written by a famous dermatologist, Dr. Sze Tai Jo. He said most of the whitening products on the market are actually sunblocks. Products with Kojic Acid, AHA, BHA and vitamin C are the ones that can truly make your skin whiter. Products with vitamin A acid, like Azelaic Acid are the stronger whitening products, but needs doctor’s prescription. Chemical called Tyrosinase can help supressing black pigment in the skin from coming to the surface.
But people with sensitive skin may be allergic to acidic products. Dr. Sze said if you really want to use it, test the products on the back of your ears or neck before you sleep. If your skin is ok in the next morning, you can contnue to use it. Dr. Sze also said to know whether the whitening is effective or not, use it for about 2 to 3 weeks. If it doesn’t work, use another product.