Benzoyl peroxide, an ally against acne.

Acne and Benzoyl Peroxide: Decoding its Effectiveness.

Acne is a skin condition that manifests through the inflammation of the pilosebaceous follicle, the area responsible for the production of sebum and hair. It can result from various factors, such as an excessive presence of the bacterium Cutibacterium acnes, repeated inflammations , an excess of sebum and an abnormal production of keratin which can lead to an accumulation of dead cells within the follicle. This in turn contributes to the blockage of pores and the formation of comedones.

Acne can be classified according to its severity into 4 main grades. Grade 1 corresponds to the stage of mild acne and is characterised by non-inflammatory comedones and a few papules. Grade 2 corresponds to the stage of mild to moderate acne and is characterised by comedones, papules and a few pustules. Grade 3 corresponds to the stage of moderate to severe acne and is characterised by larger papules, pustules and a few cysts that can affect the face, neck and upper part of the trunk. Finally, grade 4 is the most severe stage, characterised by numerous cysts.

The efficacy of benzoyl peroxide on acne.

Benzoyl peroxide appears to be an effective solution against grade 1 to 3 acne. It plays a crucial role in the elimination of acne spots by degrading Cutibacterium acnes, the bacteria responsible for inflammations. It also eliminates the excess sebum accumulated on the skin's surface as well as in the pores and exfoliates the skin by removing dead skin cells. Its effectiveness in eliminating acne spots has been demonstrated by numerous studies.

A review encompassing several databases, including a total of 2,234 participants over a 12-week period, compared the effectiveness of benzoyl peroxide used alone or in combination with other treatments, against a placebo. 72 trials involved participants suffering from severe to moderate acne and 26 trials involved patients with moderate to severe acne. The results obtained, based on patients' self-assessment criteria, suggest that benzoyl peroxide, whether used as a monotherapy or as an adjunctive treatment, could be more effective than a placebo or no treatment in improving acne. However, no numerical value was provided.

Furthermore, according to this study, it appears that benzoyl peroxide is as effective as adapalene or clindamycin, antibiotics commonly used in the treatment of acne.

The multifaceted mechanism of action of benzoyl peroxide.

Numerous studies have demonstrated that benzoyl peroxide is capable of effectively combating acne, and this is based on a combination of several distinct mechanisms of action. Indeed, it possesses antibacterial, sebostatic, keratolytic and anti-inflammatory properties.

Benzoyl peroxide possesses antibacterial properties.
When benzoyl peroxide is applied to the skin, the cysteine present in the epidermis dissociates the peroxide bond of the compound. This produces, on one hand, a benzoyl radical, which is rapidly eliminated by the body, and on the other hand, radicals, including reactive oxygen species, such as superoxide ions (O2•−) and hydroxyl radicals (HO•). These radicals interact with bacterial proteins by oxidising them, thereby disrupting their survival and functions.
According to a study published in the Journal of the National Center for Biotechnology Information, daily application of 10% benzoyl peroxide for two weeks resulted in a 98% reduction in the amount of Cutibacterium acnes in hair follicles. These results are comparable to those achieved with antibiotic therapy. However, these findings should be interpreted with caution, as the number of participants in this test was not disclosed.
Benzoyl peroxide protects sebum from oxidation.
This same study highlighted the role of benzoyl peroxide in sebum protection. It indeed allowed a 50% reduction in free fatty acids resulting from the degradation of sebum by the bacteria Cutibacterium acnes, which is responsible for inflammatory reactions. Indeed, saturated fatty acids, such as palmitic acid (C16:0), can induce the production of pro-inflammatory cytokines in sebocytes and keratinocytes, thereby exacerbating acne.
Benzoyl peroxide possesses keratolytic properties.
Simultaneously, the specific molecules obtained by dissociation of benzoyl peroxide can decompose into carbon dioxide. Indeed, benzoyl peroxide, upon contact with the skin, decomposes to produce two radicals, the benzoyl radical and reactive oxygen species. The unstable benzoyl radical splits into a phenyl radical (C6H5) and carbon dioxide (CO2). This promotes cell renewal by stimulating the detachment of dead cells from the skin surface. Indeed, CO2 mildly acidifies the environment and enhances the metabolic activity of cells, which contributes to the natural desquamation of dead cells and the overall improvement of skin health.
Benzoyl peroxide possesses an indirect anti-inflammatory action.
Finally, by reducing the bacterial load, benzoyl peroxide lessens local inflammation. Indeed, with fewer bacteria present to trigger an immune response, skin inflammations subside, and redness and spots decrease.

However, although the free radicals produced by the benzoyl peroxide are essential in the treatment of acne, their excessive presence can lead to phototoxicity. Therefore, it is important to use this product in the evening and apply sun protection the following day.