Hydroquinone

Hydroquinone is one of the most-researched and longest-used ingredients in fading and oftentimes noticeably lightening various skin discolorations, including melasma and post-inflammatory hyperpigmentation. Chemically, it is a phenol that is derived from benzene.

Hydroquinone has decades of studies backing its effectiveness in improving skin tone. It does so by inhibiting tyrosinase, an enzyme that controls the production of melanin, the pigment that gives color to skin, eyes, and hair. The root of most skin discolorations is an overproduction and uneven deposition of melanin.

In recent years, the safety of hydroquinone has been called into question for two reasons: a possible association with cancer, and the possibility of a rare condition called ochronosis that causes bluish-black or gray-blue discolorations.

In the case of ochronosis, this occurs due to overuse of hydroquinone, usually in amounts of 4% or greater and over a long period of time. Most hydroquinone preparations are in the 2% range. It should be noted that it is because of this risk of ochronosis that hydroquinone is banned in the European Union, and not for any association with an increased risk of cancer.

When it comes to cancer concerns, they are mostly related to hydroquinone’s relation to benzene, which has been demonstrated in some studies to be carcinogenic. Animal tests of hydroquinone have shown some potential to cause cellular DNA damage. A 2022 study points out though, that “it is worthwhile to know that over the last 5 decades, no cases of internal malignancy or skin cancer have been reported in scientific literature.”

Hydroquinone is available by prescription-only in the United States. Its use in topical over the counter products is not allowed by the U.S. Food and Drug Administration. It is important to consult with a health care provider if you would like to add it to your skin care routine, or ask them about alternative over-the-counter ingredients, such as tranexamic acid, niacinamide, vitamin C, and others.