On the DermTV episode, “What is Benzoyl Peroxide,” Layna from “Makeup by Layna Baaaby” asked…
“Benzoyl Peroxide has worked miracles for my skin, but I heard from a friend a while back, before I started using Benzoyl Peroxide, that it causes tumors. Is this true? I have been using Benzoyl Peroxide for years and my skin is just fine. But I’m curious!”
So Layna… Let’s discuss.
I believe Benzoyl Peroxide is safe and effective for the treatment of acne. On a practical basis, Benzoyl Peroxide was around when I started in dermatology in 1975, and so I’ve actually had experience using it for almost 40 years.
In that time, I have never seen a patient, read an article, or heard of a report that could in any way connect the use of Benzoyl Peroxide with any type of tumor or cancer in humans. Of course Benzoyl Peroxide can easily irritate skin if not used as directed, but irritation has nothing to do with causing tumors.
Let’s take it a step further.
Benzoyl Peroxide, like all peroxides, can in theory generate free radical compounds, which are some of the compounds that are implicated in causing premature aging and photo-aging of the skin, as well as the development of pre-cancerous and then possibly cancerous changes. So, if the potential free radical formation that Benzoyl Peroxide is alleged to cause were impactful, wouldn’t we really expect to see not only increased cancers and pre-cancers in Benzoyl Peroxide users, but premature aging of their skin as well?
The people in whom acne medicines like Benzoyl Peroxide are used are people who have excessive oil in their skin. And, it is a well-known fact that people with very oily skin, with or without acne, tend to have delayed aging of their skin… and look more youthful, with delayed development of lines, wrinkles and photo-aging. But these are the people who have been using Benzoyl Peroxide for years. I’m not suggesting Benzoyl Peroxide delays aging of the skin, but I’m merely saying that in the population that uses Benzoyl Peroxide, if it really did generate damaging free radicals that could cause cancer, then in those same people we should see premature aging of the skin, not delayed aging of the skin.
In terms of what’s in the scientific literature, in 1981 a study concerning the carcinogenic potential of Benzoyl Peroxide from the prestigious journal, "Science" concluded, “caution should be recommended in the use of this and other free radical generating compounds”. But in the more than 30 years since that article was published, there is very little additional work even hinting at evidence for problems in rodents, let alone humans. On the basis of lab studies on rodents, some inconclusive evidence emerged suggesting that Benzoyl Peroxide combined with ultra-violet light caused cancer in Swiss mice. There is no known relevance of cancer in mice to humans, and was it the Benzoyl Peroxide or the ultra-violet light?
Nevertheless, in 1995, the FDA, on the basis of this kind of inconclusive non human experiments, changed the status of Benzoyl Peroxide from Category 1, which is safe, to Category 3, meaning more data is needed to establish safety. THAT doesn’t mean that it’s not safe.
In humans, two cases of controlled epidemiologic studies have found a lack of association between the use of Benzoyl Peroxide and skin cancer, mirroring what we clinicians have observed for decades.
I would like to stress that in my opinion, Benzoyl Peroxide is a great ingredient… when used as directed.