How does it work?

Posted on April 3rd, by staff in Obsessions, Products, Skincare. 22 comments

How does it work?

Q: How does benzoyl peroxide work to treat mild to moderate acne?

Louise Hidinger


Our cosmetic chemist, Louise Hidinger, Ph.D., answers:

Benzoyl peroxide is a chemical compound consisting of two benzoyl groups joined by a peroxide group (two oxygen atoms, joined by a single bond).

Benzoyl Peroxide

Peroxide compounds such as benzoyl peroxide are unstable as the oxygen-oxygen bond is weak. As a result, peroxides tend to decompose to release free radicals.

When benzoyl peroxide is applied to skin, it works to treat acne by two different modes of action which act in combination:

  • Benzoyl peroxide decomposes to release free radicals, which kill P. acnes bacteria associated with acne. These free radicals eventually decompose to form benzoic acid and oxygen.
  • The benzoic acid formed by benzoyl peroxide decomposing is a keratolytic agent, helping to break down the keratin in the outermost layer of the epidermis, thus speeding up the shedding of dead skin cells from this layer, as well as aiding in the clearing of sebum and cellular debris from pores. This helps to lower bacterial populations in the pores and on the skin, which in turn helps to prevent further acne breakouts.

In addition, benzoyl peroxide is lipophilic (“oil-loving”). This is an important property as it allows benzoyl peroxide to penetrate readily into the outermost layer of the epidermis and enter pores that contain sebum and P. acnes bacteria – the areas where it is most needed!



Try our derm’s Acne Clarifying Treatment, a gel-based 5% benzoyl peroxide formula ($75,

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