Hydroquinone is one of the most effective treatments for hyperpigmentation, but also one of the most controversial. Loved by dermatologists, it has however been banned in some countries, including South Africa and France, following concerns of increased cancer risk and ochronosis. Even the FDA has recently proposed a ban, despite scientific studies showing that would be an “unnecessarily extreme“. So, who’s right? Is hydroquinone really that dangerous?
How does hydroquinone work?
Hydroquinone works by inhibiting the activity of tyrosinase (the enzyme that controls the synthesis of melanin) and by increasing the cytotoxicity of melanocytes (cells that produce melanin). This makes it very effective at treating sun spots, melasma, freckles, postinflammatory hyperpigmentations and other forms of skin discolouration. In the US, hydroquinone can be used only in concentrations of up to 2% in OTC products, and up to 4% in prescription products. If you decide to use one, make sure it is packaged in an air-tight, opaque tube or bottle. When exposed to light and air, it oxidizes (you can see this happening, because hydroquinone warns you by turning brown) and loses its efficacy.
Does hydroquinone cause cancer?
Scientific studies have found that hydropquinone can cause cancer in rats. However, these were performed by injecting or feeding them with high amounts of hydroquinone. Therefore, these results don’t translate to humans, who only topically apply low standard concentrations on limited areas of their skin. In addition, Dr Levitt, in his The safety of hydroquinone: A dermatologist’s response to the 2006 Federal Register notes that, while with hydroquinone use, murine (mouse) hepatic adenomas (benign liver tumours) increased, murine hepatocellular carcinomas (cancerous liver tumours) decreased. This suggests that hydroquinone may actually have a protective effect. Dr. Goldberg, a clinical professor of dermatology at the Mount Sinai School of Medicine also believes hydroquinone isn’t dangerous. In a 2007 issue of Elle magazine, he claimed: “Over 100 scientific articles confirm it is a safe topical for humans; no independent studies prove the opposite.”
Does hydroquinone cause ochronosis?
Ochronosis is a bluish black discoloration of the skin caused by a build-up of tyrosine or phenylalanine. Although it affects mainly people with black skin, it can occur in Hispanics and Caucasians as well. Its incidence is, however, low. According to Dr Levitt, “a literature review of exogenous ochronosis and clinical studies employing hydroquinone (involving over 10,000 exposures under careful clinical supervision) reveal an incidence of exogenous ochronosis in the United States of 22 cases in more than 50 years”.
It is not clear why this happens but possible causes may be the use, in conjunction with hydroquinone, of resorcinol (another agent used to treat hyperpigmentation) and excess sun exposure. Hydroquinone can thin skin, making it more photosensitive. As a result, the sun causes your skin to produce more melanin, which counteracts, in part, the efficacy of hydroquinone. Therefore, if you want to use it, don’t skip the sunscreen (actually, you should never do that anyway).
Can hydroquinone cause irritations and allergies?
The small concentrations of hydroquinone used in skincare products don’t cause cancer, and only rarely ochronosis. But they can cause redness and irritations in people with sensitive skin. In some cases, an allergic reaction can occur. To reduce the potential irritation, many dermatologists recommend to use hydroquinone in four-month cycles. This means using a product with hydroquinone for four months, then switching to an alternative treatment (such as kojic acid or azelaic acid) for another four months, then going back to hydroquinone for another four months, and so on.
The bottom line
Hydroquinone is one of the most effective ways of treating any type of hyperpigmentation. While it doesn’t cause cancer, it can cause allergies and irritations in people with sensitive skin. Those with dark skin, who are more prone to developing ochronosis, may want to consult a dermatologist before using hydroquinone. In any case, this ingredient should be used in four months cycles, always in conjunction with sunscreen, and never with products that contain resorcinol.
Do you use products with hydroquinone?