Benzoyl Peroxide is the main ingredient in skin care products that treat and prevent acne and some related skin conditions such as folliculitis.  The way these products are formulated with benzoyl peroxide (BP) plays a role in the levels of toxic carcinogenic chemical found, “benzene”, according to new research.

Concerns about the potential for BP products to break down into benzene, a known carcinogen, have been ongoing, and this is the latest research.

In this recent study published in JAMA Dermatology, volume 161, number 4, 2025 researchers examined the association of product formulation with benzene levels in 111 over-the-counter BP products. The study found that the production process and ingredient composition had a significant association with benzene levels.

Barbieri and his colleagues evaluated the vehicles for the 111 products that had previously had their benzene levels evaluated by researchers at Valisure, an independent lab that tests the purity and safety of drugs and consumer products and reported its findings in 2024.

In that report, the Valisure researchers concluded: “Results suggest that potential benzene exposure from formation during BPO drug product use poses significant risks independent of the starting benzene concentration.”

In the new study, researchers found a median benzene concentration of 0.89 and a range of 0.19-35.3 parts per million (ppm); the US Food and Drug Administration (FDA) sets a limit of 2 ppm (interquartile range, 0.39-2.48).

The study categorized products by use, such as leave-on or wash-on; concentration of BP; and days until expiration date (a measure of product age). They also looked at whether the product had a formulation, based on the ingredient list, which could indicate higher temperatures encountered by BP during formulation (such as hot processing), antioxidants (such as butylated hydroxytoluene [BHT]), and more acidity of the product (which could quench free radicals before they could turn into benzene).

Products included brands such as Clearasil, Neutrogena, Proactive, Equate, Up&Up, Walgreens, CVS Health, and others.

Their findings were as follows:

• Leave-on products, which are often made in smaller batches and may cool more quickly, were associated with significantly lower concentrations of benzene.
• No significant association was found between BP and benzene concentrations for some products.
• A weak but statistically significant association was found between days to expiration date and benzene concentration.
• In a regression model analyzed and adjusted for BP concentration, product type, and days until expiration, conditions consistent with hot processing were linked with increased benzene concentration and the use of antioxidants such as BHT with decreased benzene concentration.
• Each 100 days of storage at room temperature is linked with an increase of < 1 ppm of benzene. That suggests benzene is not forming at room temperature at any meaningful degree.

The findings could be of value to manufacturers who may want to consider how to reduce or avoid heat during manufacturing to keep benzene levels as low as possible.

The new research finding about the importance of formulating benzoyl peroxide products highlights that many benzoyl peroxide products are unstable and form benzene. Formulation is likely the strongest contributor to benzene content in benzoyl peroxide drug products.

Manufacturers should reformulate with a goal of reducing benzene formulation but to date, I have not been able to find such manufacturing efforts nor have I seen substantiative action from the FDA.

The presence of benzene is extremely concerning and manufacturers should focus their efforts to eliminate or at least substantially reduce benzene concentrations in their benzoyl peroxide products.