Does Benzoyl Peroxide Cause Cancer?

Hillary’s concerned question: I’m hoping the Beauty Brains can help clear up an issue for me. I use benzoyl peroxide to help treat my acne. Recently I’ve been hearing a lot of buzz about how it might cause cancer and promote premature aging. Some of the sources of this information are suspect as they seem to be pushing products that do not contain benzoyl peroxide, however, a quick search in Pub med did turn up some studies that benzoyl peroxide combined with ultraviolet light caused cancer in Swiss mice. Is this an issue that you can help shed some light on? Thanks!

The Left Brain’s acne answer:
Hillary, kudos to you for looking up articles on Pub med rather than believing what you read on some company’s website.

Benzoyl Peroxide and cancer

We looked at the article you found and it does indeed implicate benzoyl peroxide in both papillomas and carcinomas. However, the article is a bit vague. It says benzoyl peroxide was carcinogenic only when used with an initiator, which doesn’t occur with normal use. Secondly, it said benzoyl peroxide produces an effect similar to another compound that causes tumors but there is not directly link to cancer. Finally, I noticed that this study is from 1981 so there’s been plenty of time for follow up research.

The latest research

Further literature review turns up several sources that show benzoyl peroxide has been cleared in later studies. To be fair, one reference did say scientists should keep their eye on the subject, just to be safe. In addition, it is also true that in 1995, the FDA changed the status of benzoyl peroxide from Category I (safe) to Category III (more data is needed.) I have not been able to find a current update on the status of benzoyl peroxide.

References

“Acne and Rosacea: Third Completely Revised and Updated Edition”, 2000:

Following application to the skin, benzoyl peroxide is rapidly metabolized to benzoic acid, a harmless chemical. Extensive use in human beings has failed to demonstrate absorption. The drug is eminently safe.

The British Journal of Dermatology, 1990:

So far no skin malignancies after the clinical use of benzoyl peroxide has been reported. A possible relationship between the use of the compound and the occurrence of malignant melanoma has been looked at in two case-control studies, both with negative results…However, since the average latent period for skin carcinogenesis is of the order of 15-25 years, this requires further follow-up…Thus, the question of carcinogenic potential of benzoyl peroxide is as yet not fully answered, but at the present time it seems likely that this compound is safe to use.

Regulatory Toxicology and Pharmacology, 1995:

Topical benzoyl peroxide has been used in the treatment of acne for over 30 years, with no reports of adverse effects that could be related to skin carcinogenesis. Two case-control epidemiological studies have found a lack of association between the specific use of benzoyl peroxide and skin cancer. In addition to these findings in humans, 23 carcinogenicity studies in rodents with benzoyl peroxide, including 16 employing topical application, have yielded negative results. An increase in skin carcinomas was reported in 1 study in which benzoyl peroxide in acetone was applied to the skin of SENCAR mice for a 1-year period; however, this study did not employ adequate control groups to fully understand the unusual findings, and the results were inconsistent with those of 6 other similar studies.

The moral of this story is to never believe any single scientific study. Any one study can be flawed, you need to look at body of work of the research to be sure.