Hydroquinone is a strong inhibitor of melanin production that has long been established as the most effective ingredient for reducing and potentially eliminating melasma (Source: Journal of Dermatological Science, August, 2001, Supplemental, pages 68-75). In different concentrations it inhibits or prevents skin from making the substance responsible for skin color. Hydroquinone does not bleach the skin, which is why calling it a “bleaching agent” is a misnomer; it can’t remove pigment from the skin cell. But blocking the skin’s ability to synthesize melanin absolutely can reduce and eliminate the brown discolorations, whether they are caused by sun damage or hormonal influences. Over-the-counter hydroquinone products can contain 0.5% to 2% concentrations while 4% concentrations of hydroquinone (and sometimes higher) are available only from physicians.
Even though hydroquinone, applied topically, has proven to be the most effective ingredient for skin lightening and has been available without a prescription for more than 50 years in the United States, some concerns have been raised about its safety. Yet research indicates skin reactions are rare and minor, or a result of using extremely high concentrations of hydroquinone, or of using hydroquinone products that have been adulterated with dangerous ingredients.
Hydroquinone-based products were banned in South Africa years ago where problems were most frequently seen. However, hydroquinone products in South Africa and other countries are notorious for containing mercury and glucocorticoids, among other caustic and illegal contaminants, which were believed by many to be the cause of the disorders experienced (Sources: International Journal of Dermatology, February 2005, pages 112-115; and British Journal of Dermatology, March 2003, pages 493-500).
There is abundant research showing hydroquinone to be safe and extremely effective. (Sources: Cutis, April 2008, pages 356-371 and August 2006, pages S6-S19; Journal of Cosmetic Laser Therapy, September 2006, pages 121-127; American Journal of Clinical Dermatology, July 2006, pages 223-230; and Journal of the American Academy of Dermatology, May 2006, pages S272-S281.)
Interestingly, hydroquinone happens to be a potent antioxidant (Source: Journal of Natural Products, November 2002, pages 1605-1611).
Questions concerning hydroquinone in terms of it being a carcinogen have also been addressed in the research. Problematic incidences have been shown when hydroquinone was fed or injected into rats in large doses, though with topical use there has been no research showing it to be mutagenic on humans or animals (Source: Critical Reviews in Toxicology, November 2007, pages 887-914). In fact, there is even research showing that workers who handle pure hydroquinone actually have lower incidences of cancer than the population as a whole (Source: Critical Reviews in Toxicology, May 1999, pages 283-330).
Dr. Susan Taylor, founding director of the Skin of Color Center in New York City and assistant professor of dermatology at Columbia University stated, “Hydroquinone is the gold standard for treating pigmentation disorders and has been for many years. I consider it to be very safe and effective” (Source: Pittsburgh Post-Gazette, Wednesday, September 6, 2006).
Tri-Luma Cream ($101 for 1.05 ounce) is a prescription-only medication containing fluocinolone acetonide 0.01% (a form of cortisone), hydroquinone 4%, and tretinoin 0.05% for skin lightening. There is a good deal of research showing this combination to be a triple-threat for skin discolorations. Even though it is pricey, in comparison to many skin-lightening products available at cosmetics counters and spas this one is a bargain. It also has research showing it works. (Source: British Journal of Dermatology, September 2008, pages 697-703.)
Whether or not you consider using hydroquinone in a skin-care product is up to you. What is abundantly clear is that hydroquinone is a well-researched ingredient, incredibly effective for its intended purpose, and that no other ingredient can begin to compare with its effectiveness.
Hydroquinone can be an unstable ingredient in cosmetic formulations. Upon exposure to air or sunlight it can turn a strange shade of brown. It is thus essential when you are considering a hydroquinone product to be sure it is packaged in a non-transparent container that doesn’t let light in and that minimizes the amount of air exposure. Hydroquinone products packaged in jars are not recommended because once opened they quickly become ineffective.
(Sources: Journal of Drugs in Dermatology, September-October 2005, pages 592-597; Journal of Dermatological Science, August 2001, p ages S68-S75; Critical Reviews in Toxicology, May 1999, pages 283-330; Journal of Cosmetic Science, May-June 1998, pages 208-290; and Dermatological Surgery, May 1996, pages 443-447.)