Hydroquinone, aka benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. Its chemical structure features two hydroxyl groups bonded to a benzene ring in a para position. It is a white granular solid. Substituted derivatives of this parent compound are also referred to as hydroquinones. The name "hydroquinone" was coined by Friedrich Wöhler in 1843. In human medicine, hydroquinone is used as a topical application in skin whitening to reduce the color of skin. It does not have the same predisposition to cause dermatitis as metol does. In 2006, the United States Food and Drug Administration revoked its previous approval of hydroquinone and proposed a ban on all over-the-counter preparations. The FDA stated that hydroquinone cannot be ruled out as a potential carcinogen. This conclusion was reached based on the extent of absorption in humans and the incidence of neoplasms in rats in several studies where adult rats were found to have increased rates of tumours, including thyroid follicular cell hyperplasias, anisokaryosis (variation in nuclei sizes), mononuclear cell leukemia, hepatocellular adenomas and renal tubule cell adenomas. One of the components in TRI-LUMA Cream, hydroquinone, is a depigmenting agent, and may interrupt one or more steps in the tyrosine-tyrosinase pathway of melanin synthesis. However, the mechanism of action of the active ingredients in TRI-LUMA Cream in the treatment of melasma is unknown.

Arbutin, the beta-D-glucopyranoside of hydroquinone, is a skin whitening cosmetic ingredient. Compared with hydroquinone, arbutin is a less potent skin hyperpigmentation agent, but less toxic. Arbutin is found in a number of edible berry-producing plants such as blueberry and cranberry, marjoram, and most pear species. Chinchircoma (Muticia acuminatai) that contains arbutin, has been traditionally used by South American populations internally the fresh juice is used for gastric ulcers and internal tumors; the water of boiled leaves and flowers for illness of the respiratory tract; for hearth disorders or pain. According to pharmacological results in vitro, liver protective effects as well as anti-inflammatory activity were proven. It can also be beneficial for asthma and other anaphylactic reactions. This plant is component of the lsula Rain’s botanical products (Peru): ‘I-Day Digestive Cleanse #2.Herbal Supplement approved by FDA. As a hyperpigmentation agent arbutin inhibits tyrosinase and thus prevents the formation of melanin.