Areas of increased pigmentation such as moles may be depigmented to match the surrounding skin. Effective agents for specific areas include corticosteroids, tretinoin, and hydroquinone. These agents, however, are not allowed in cosmetics in Europe due to concerns of side effects. Attempts to whiten large areas of skin may also be carried out by certain cultures. This may be done for reasons of appearance, politics, or economics. Skin whiteners can help you achieve lighter skin tones, many of them contain harmful ingredients like the steroid clobetasol propionate, inorganic mercury (mercuric chloride or amalgamated mercury), glutathione (an antioxidant traditionally used in cancer treatment), and the organic compound hydroquinone. Skin lighteners' main health risks are linked to: i) The overuse of topicalclobetasol, which can cause systemic steroid effects from daily usage, especially on broad skin regions; and (ii) concealed mercury content, which can lead to mercury poisoning depending on individual susceptibility. Many skin whiteners contain a toxic form of mercury as the active ingredient. Their use, therefore, may harm a person's health and is illegal in many countries. Hydroquinone is a commonly used agent in skin whiteners, though the European Union banned it from cosmetics in 2000. It works by decreasing melanin production. Tretinoin, also known as all-trans retinoic acid, may be used to whiten specific areas. It may be used in combination with steroids and hydroquinone. Alpha hydroxy acid (AHA) is also used as a skin bleacher, but its biochemical mechanism is unclear. Side effects may include sun sensitivity, skin redness, thickening, or itching. Low concentrations may be used in cosmetics. Kojic acid has been found to be an effective lightener in some studies, and is also allowed to be used in cosmetics. Side effects, however, include redness and eczema. Glutathione is the most common agent taken by mouth in an attempt to whiten the skin. It may also be used as a cream. It is an antioxidant normally made by the body. Whether or not it actually works is unclear as of 2019. Due to side effects that may result with intravenous use, the government of the Philippines recommends against such use. One 2017 review found tentative evidence of benefit of tranexamic acid in melasma, while another 2017 review found that evidence to support its use was insufficient. Azelaic acid may be a second-line option for melasma. A number of types of laser treatments have been used in melasma with some evidence of benefit. Reoccurrence, however, is common and certain types of lasers can result in more pigmentation.
Skin whitening
Dark skin
Hypopigmentation
Erythema
Dryness 
Tooth discoloration
Hyperpigmentation
Oral pigmentation