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So…what’s up with all the scary articles that came out last week saying there’s a cancer-causing chemical in benzoyl peroxide products? As someone who’s been buying acne creams and face washes since the early aughts, many of which have had benzoyl peroxide in them, I wanted to know more about the study behind those alarming headlines.
In a nutshell, the research in question—which was conducted by the independent lab Valisure in New Haven, Connecticut—suggests that acne treatments containing benzoyl peroxide can lead to the development of high levels of benzene, a known carcinogen (the term for any substance that can cause cancer). The lab’s report claims that this can happen within a product’s formula and also in the air around it, particularly if it sits in an environment at or above 158 degrees Fahrenheit (the temperature the researchers used to approximate a hot car) for more than 16 hours.
Previous research has established that benzoyl peroxide can decompose into “a dense white smoke” consisting of benzene and other compounds. This particular finding comes from a CDC report that also specifies that this reaction occurs when benzoyl peroxide is exposed to excessive heat, specifically 158–176 degrees Fahrenheit—so, on the lower end, the exact temp used in the Valisure study to trigger the reaction.
While a nearly 17-hour hot-car session at that temperature sounds like an extreme test for any skin care product (a real car would cool after the sun went down), it does beg the question: If benzoyl peroxide can degrade into benzene in certain environments, how worried should you be about your acne treatments?
Is it really time to freak out about cancer-causing chemicals in benzoyl peroxide acne products?
The short answer: If you don’t let them bake in your car, then you probably have nothing to worry about, as far as experts know. According to indoor air quality guidelines from the World Health Organization (WHO), inhalation accounts for 95 to 99% of most people’s exposure to benzene, followed by food and water consumption. Common sources of the carcinogen in indoor and outdoor air include building materials, furniture, garages (thanks to car exhaust), heating and cooking systems, and cigarette smoking. (Note that zit cream is nowhere on that list.)
The exact levels in the air vary by city and environment, but most studies linking benzene to cancer were conducted on people who live or work in an industrial setting. For example, research on workers in the petroleum industry has shown that benzene exposure can increase the risk of leukemia (a cancer of the body’s blood-forming tissues) and multiple myeloma (a condition in which cancerous plasma cells infiltrate bone marrow), per the WHO guidelines. There’s no solid evidence, however, connecting benzene from acne products to cancer.
The new study on benzene in acne products is flawed in many ways.
Okay, back to the Valisure study: This research was not published in a peer-reviewed journal, which would have required other experts to evaluate how well the study was conducted and how legit its results are. Valisure’s paper was only published on the lab’s own website and submitted as a “citizen petition” (a way for individuals or groups to ask the FDA to issue, amend, or revoke a regulation).
“The lab that recently identified the presence of benzene in the many benzoyl peroxide-containing products is the same lab that reported the presence of benzene in spray sunscreens and hand sanitizers over the past few years,” Joshua Zeichner, MD, the director of cosmetic and clinical research in dermatology at Mount Sinai Hospital in New York City, tells SELF. “The lab’s practices have been questioned since many of its findings have not been able to be replicated.” On social media, some cosmetic chemists and dermatologists who delved into the study also alleged that there were various factual errors in the paper.
Also worth taking into account: Valisure’s CEO, David Light, filed a patent for a shelf-stable formulation of benzoyl peroxide last year, so there’s an additional layer to the publication of this study calling for a recall of existing acne products, given that Light is aiming to make money selling an alternative.
There’s a large body of peer-reviewed evidence showing that benzoyl peroxide is a potent pimple fixer. “It’s a staple, and perhaps the most effective of acne treatments,” Dr. Zeichner says. “It works by lowering levels of acne-causing bacteria, reducing inflammation in the skin, and helping to open up the pimples themselves. It’s particularly great for treating red, angry zits.”
The bottom line? “More research is needed before telling patients to discontinue their medication,” Geeta Yadav, MD, a board-certified dermatologist and the founder of FACET Dermatology in Toronto, tells SELF. In the meantime, there are a couple of tips you can tuck in your pocket to make sure your products are only doing you good, regardless of the petition’s legitimacy.
The number one thing you can do to make sure your acne-fighting treatment doesn’t decompose into something unsavory is to throw it out on time. “All skin care ingredients expire, including benzoyl peroxide,” Ginger King, MA, a cosmetic chemist based in Parsippany, New Jersey, tells SELF. You’ll need to check your tube or bottle for the exact date: “Most products have undergone significant stability testing and will list an expiration of two to three years after production,” Dr. Zeichner says. In other words, if you purchased it before COVID turned our lives upside down, it’s got to go.
Not only can expired skin care products be chemically unstable, but they probably won’t work as well: “In most cases, active ingredients, including benzoyl peroxide, will get weaker toward the end of a product’s shelf life,” Dr. Yadav says.
Even if the research was a bit dodgy, King says you’re best off following the same advice she would give about any other beauty product: “Do not leave it in a hot car.” Keeping it anywhere in your bathroom should be just fine (it’s definitely going to stay under that 158-degree mark, even if you love a steamy shower), but if you want to be hyper-vigilant, store it in a cool and shady spot, such as your bathroom cabinet, she says.
If you decide to ditch benzoyl peroxide for whatever reason, you can work with a dermatologist to find other alternatives.
“If you don’t feel comfortable continuing to use benzoyl peroxide, that’s okay,” Dr. Yadav says. “I’d highly recommend speaking to a dermatologist, though, who can work with you to go over your options.”
Depending on the triggers for your particular acne, these pros are likely to recommend trying research-backed alternatives that contain ingredients like salicylic acid (a beta hydroxy acid that removes excess oil and dead cells from the skin’s surface to keep pores unclogged), sulfur (which has antimicrobial and anti-inflammatory properties to prevent and treat zits), or the topical retinoid adapalene (which is sold under the brand name Differin and can prevent skin cells from sticking together, Dr. Zeichner says).
The bottom line: Your pimples, your choice. Just know that there’s no solid scientific evidence to suggest that benzoyl peroxide acne products cause cancer. And if that changes in the future, we’ll be the first to let you know.
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