<unk> , also known as skin lightening and skin bleaching, is the practice of using chemical substances in an attempt to lighten the skin or provide an even skin color by reducing the melanin concentration in the skin. Several chemicals have been shown to be effective in<unk> , while some have proven to be toxic or have questionable safety profiles. This includes mercury compounds which may cause neurological problems and kidney problems. In a number of African countries, between 25 and 80% of women regularly use<unk>  products. In Asia, this number is around 40%. In India, specifically, over half of skin care products are sold to whiten skin. In Pakistan, where skin lightening products are popular, creams have been found to contain toxic levels of hydroquinone and mercury. Efforts to lighten the skin date back to at least the 1500s in Asia. While a number of agents—such as kojic acid and alpha hydroxy acid—are allowed in cosmetics in Europe, a number of others such as hydroquinone and tretinoin are not. While some countries do not allow mercury compounds in cosmetics, others still do, and they can be purchased online.
Skin whitening
Dark skin
Hypopigmentation
Erythema
Dryness 
Tooth discoloration
Hyperpigmentation
Oral pigmentation