Does Hydroquinone Really Cause Cancer?

Despite our best intentions, we all get a little more sun exposure than we would like to during the summer. Now that summer has ended, many individuals want to perk up their less than lustrous post-summer skin. Which is probably why I've been getting so many people inquiring about hydroquinone...either wanting to know if it is safe to use on their skin or to make sure they are not using any products with a trace of hydroquinone in it even though they want to get rid of some skin hyperpigmentation from excess sun exposure. Some people say that it causes cancer yet the FDA still allows the use of hydroquinone in the U.S., either in OTC or prescription strength formulations. So what exactly is hydroquinone? Why all the fuss and concerns associated with it? Can it really cause cancer?

What is Hydroquinone?

Hydroquinone is a topical agent for reducing skin pigmentation. It is available in OTC strength of up to 2% and in prescription strength concentrations, usually at 4% or higher. People typically use hydroquinone to lighten skin affected by hyperpigmentation, freckles, melasma and age spots. It is a component of the herbal remedy uva ursi.

In 1982, the National Toxicology Program (NTP) published a rule to propose that OTC skin products containing 1.5-2% hydroquinone are generally recognized as safe and effective. In 2006 this rule was withdrawn because of evidence indicating that hydroquinone may act as a carcinogen in rodents after oral administration. Hydroquinone has also been linked with ochronosis, a medical condition in humans which causes skin darkening and disfiguration, when it is applied topically. In the 2006 proposed rule, the NTP recommended that additional studies be conducted in order to determine if there is a risk to humans from the use of hydroquinone. In the meantime as more studies are being conducted that started in 2009, the NTP believes that hydroquinone should remain available as an OTC skin product.

Three Concerns Associated with Hydroquinone

So when some individuals express concern about hydroquinone possibly causing cancer, here are the three main reasons where this concern is coming from:

Concern #1: The British Cancer Journal published a study that linked very high doses of hydroquinone to cancer in mice. A second study found similar results. Subsequently, hydroquinone was banned in Europe, Australia and parts of Asia and Africa. Rodent studies linking something to cancer is a concern, but to date there are no studies that show hydroquinone affects humans in the same way. Also, because hydroquinone makes the skin more vulnerable to UV rays, there is concern that it is linked to increased skin cancer risk. This is why it is so important to always use a broad spectrum SPF 50 sunscreen when using skincare products that contain hydroquinone.

Concern #2: Hydroquinone is thought to cause a medical condition called ochronosis, which encourages the appearance of dark blue and black skin pigment. Although uncommon, particularly with OTC concentrations, some people have developed a dark blue and black skin discoloration after using it. Ochronosis can also cause grayish-brown spots and tiny yellow and brown bumps, as well as skin thickening. This condition is mainly associated with dark-skinned individuals using high concentrations of hydroquinone for a long time. However, most dermatologists in the U.S. report not having ever treated a patient with ochronosis due to using hydroquinone. Ochronosis has only been documented in dark-skinned patients.

Concern #3: Hydroquinone has been known to cause skin redness and irritation, which can lead to increased patches of irregular pigmentation in dark-skinned individuals. Because of its potential for skin irritation, doctors agree that it should not be used on skin that is already sunburned, dry, chapped or inflamed.

Other Important Details Regarding Hydroquinone Use

Here are several additional important details regarding hydroquinone use:

Hydroquinone works by inhibiting the enzyme tyrosinase, which is important for the development of skin melanin. As long as you continue to use it, you will inhibit tyrosinase and pigment production. Unfortunately, when you discontinue use of hydroquinone, your skin’s natural supply of tyrosinase will no longer be inhibited. Slowly but surely, your skin’s natural pigmentation will return.

Hydroquinone should be used in 2-4 month cycles (some dermatologists recommend 2 months while others recommend 4 months), alternating in the off months with milder tyrosinase inhibitors such as kojic acid, azelaic acid, arbutin and other skin lightening agents (especially if you have darker skin).

Do not use any skincare products containing benzoyl peroxide while you are using hydroquinone. This may cause temporary staining of the skin. This staining can typically be removed with soap and water, but it’s still best to avoid any products containing benzoyl peroxide.

Do not use any products containing resorcinol while you are using hydroquinone. Ochronosis is well documented in dark-skinned individuals when combining resorcinol products and hydroquinone. Moral of the story, play it safe…don’t combine any products containing resorcinol or any other skin lightening treatment when using hydroquinone, period.

Hydroquinone has been known to cause pigmentation of the eye and permanent corneal damage when the eye is directly exposed to it. Avoid the eye area at all costs when applying skincare products that contain hydroquinone.

Key Takeway

So while hydroquinone is a concern for many, the key takeaway is that hydroquinone has NOT been directly linked to cancer in humans, only mice. This rumor arose from a study that demonstrated mice exposed to hydroquinone developed liver tumors. However, these results were reported in a misleading fashion, as dermatological experts explained in a 2006 review in the Journal of the American Academy of Dermatology.

Rodent studies involving VERY HIGH DOSES of hydroquinone administered by feeding tube showed the potential to cause cancer, according to the FDA. However, no carcinogenic properties have been associated with topical or oral hydroquinone use in humans. So, if you're a human and use the standard preparations, then hydroquinone seems safe to use. Also, the track record speaks to the safety of hydroquinone itself. Some suggestions exist that there may be problems when pharmacies compound hydroquinone in higher concentrations than the approved 4% level, but again NO STUDIES have proven hydroquinone causes cancer in humans when used topically.

So the bottom line is that hydroquinone certainly raises some valid concerns to think about. But it’s still the most effective skin lightener on the market today. It appears to work well with other ingredients like vitamin C, Retin A, retinol and alpha hydroxy acids. You can use lower concentrations of 1.5-2% and get additional benefits from these complementary ingredients. Always keep the concentration of hydroquinone as low as possible. OTC preparations can have up to 2% while those available by prescription usually have around 4% hydroquinone. Always buy products containing hydroquinone if they are only made in the U.S. Mercury has been banned for many years and this seems to be a major source of issues in skincare products that contain hydroquinone made in other countries.

Looking for a skincare regimen to help with uneven skin tone, dark spots, hyperpigmentation and dullness? REVERSE offers two options, one with 2% hydroquinone and one without it. Take this simple, free skincare assessment and find out which products are right for you!

Sources:

https://www.fda.gov/AboutFDA/CentersOffices/OfficeofMedicalProductsandTobacco/CDER/ucm203112.htm

https://rarediseases.info.nih.gov/diseases/7231/ochronosis

https://www.aad.org/Posters/Documents/AM2012/Poster/4581/4581.pdf

https://www.drugs.com/cons/resorcinol-topical.html

https://www.tandfonline.com/doi/abs/10.3109/09546639709160504

https://www.jaad.org/article/S0190-9622(07)00431-8/abstract?cc=y=