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Activities:
Tyrosinase inhibition
Important Chemical Components:
Chemical formula: 1,4 dihydroxybenzene
Origin Classification:
Derived from natural sources, but synthetic in topically applied form
Personal Care Category:
Depigmenting, brightening, lightening
Recommended for the following Baumann Skin Types:
DRPT, DRPW, DSPT, DSPW, ORPT, ORPW, OSPT, and OSPW. Hydroquinone (HQ) should be used with caution in sensitive skin types 2 and 4 because it may cause skin redness and irritation.
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Hydroquinone (HQ), a hydroxyphenolic derivative of benzene, occurs naturally as an ingredient in various plant-derived foods and beverages, such as vegetables (e.g., onions), fruits (particularly cranberries, blueberries, and pears), grains (especially wheat, wheat germ, and rice), coffee, tea, beer, and red wine.1–3 It is known to cause reversible inhibition of cellular metabolism by affecting both DNA and RNA synthesis. For many years, HQ has been the first-line therapy for postinflammatory hyperpigmentation and melasma. It is known to act as one of the most effective inhibitors of melanogenesis in vitro and in vivo (Table 36-1).4
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In 1936, Oettel was the first to report that HQ exhibited a lightening effect on the coat of black-hair cats that was reversible after drug withdrawal.2,5 Martin and Ansbacher were able to duplicate these results in 1941 in mice.2,6 The use of HQ to lighten the skin finally emerged in the 1950s after anecdotal reports from the southern United States of depigmentation resulting from the use of sunscreens containing HQ.1,7 Dermatologists first started using HQ as a depigmenting agent in 1961, after Spencer’s report that 45 percent of 98 subjects treated with 1.5 and 2 percent HQ showed improvement in hyperpigmentation without adverse side effects.2,7 HQ has been used safely and effectively since that time for hypermelanosis, senile lentigos, vitiligo, and melasma, and has long been considered the most effective skin-lightening product for hyperpigmented skin disorders and the gold standard of treatment.1,2,8–10
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Concerns about its safety and potential to cause cancer, however, led to its ban for general cosmetic purposes in Europe at the beginning of the millennium. In Asia, HQ is legal, but highly regulated. In the United States, the Food and Drug Administration (FDA) has long been considering the status of HQ but not yet decided whether to ban it in over-the-counter (OTC) products. HQ has never been etiologically linked with human cancer and has been safely used by dermatologists in the United States ...