Is hydroquinone safe to use?

Hydroquinone (HQ) is a topically-applied medication that inhibits tyrosinase, the enzyme that converts tyrosine to melanin in the skin.

It is the most effective (if perhaps the only effective) topical treatment for pigmentation and has a strong evidence base for its efficacy and safety. It was first used without a prescription as a sunscreen in the 1950s and was found to lighten skin so in 1961 the first clinical trial was undertaken to treat skin pigmentation.

It is one of the longest-standing topical treatments we have in dermatology, with a massive amount of high-quality safety and efficacy data to support its use (Levitt, 2007). There are, however, persistent concerns in the media and on the internet about its safety. The main two safety concerns are about exogenous ochronosis (EO) and cancer. I have discussed EO before so this post will focus on the cancer side.

The question is: Does HQ cause cancer? The short answer: No.

There are numerous studies looking at human exposure to hydroquinone and there has not been a single cancer reported. There are some pretty crazy studies out there too – like one in which two men ate 500 mg of hydroquinone per day for 5 months and did not develop any cancers or problems with their kidneys or bone marrow (Decaprio, 1999). The two papers I have referenced here are only two of the many, many high-quality peer-reviewed publications about the safety and efficacy of this topical treatment. There is a lot of negative publicity about HQ (as is the case with many prescription treatments) which has no evidence base and no logic behind it. I would suggest that much of the negative press is propagated by cosmetic companies that see the use of HQ as a threat to the sale of their own (very expensive) ‘anti-pigment’ cosmetic products.