Can benzoyl peroxide help to reduce the severity of scars?

Acne is a chronic skin disease which, depending on its progression, is characterised by the emergence of various skin eruptions (open or closed comedones, pustules, papules, nodules or cysts), indicating the severity level of the disease. It can lead to more or less significant inflammations that damage the tissues surrounding the pore and can create "pits" in the skin, leading to the formation of scars. On the other hand, improper treatments given to this issue (excessive exfoliation, scratching, etc.) can accentuate the appearance and depth of the scars. Today, several techniques are available to diminish the acne scars and reduce their impact on the patients' quality of life.

According to some sources, in addition to its antibacterial, sebum-regulating and anti-inflammatory properties that make it a preferred treatment for acne spots, the benzoyl peroxide would be an effective method for improving the appearance of scars. Indeed, it would limit the formation of new inflammatory lesions and thus reduce the likelihood of additional scarring. Benzoyl peroxide also has exfoliating properties that could be utilised to combat scars.

However, no study demonstrates the effectiveness of the topical application of benzoyl peroxide alone in reducing scars.

However, some research suggests that when combined with retinoids, such as adapalene, benzoyl peroxide may have regenerative effects. In the Journal of Dermatological Treatment, an initial multicentre study conducted on 31 subjects with moderate acne (20 to 40 inflammatory lesions and a minimum of 10 atrophic scars) aimed to evaluate the effectiveness of a gel containing 0.1% adapalene and 2.5% benzoyl peroxide on reducing and preventing the progression of acne scars. A significant decrease in the number of inflammatory lesions was observed. Indeed, the proportion of patients with few lesions increased from 9.7% to 45.2% after 24 weeks and a better overall scar assessment score was achieved compared to the placebo. Furthermore, it was noted that the number of scars on the treated side remained stable, while it increased on the placebo side, indicating that the treatment appears to prevent the formation of new scars. However, the small number of patients is not sufficient to confirm the effect of this combination on acne scars.

In order to confirm this hypothesis, another similar multicentre study (OSCAR) was conducted on 503 patients. The results indicate that within 24 weeks, the combination of adapalene/benzoyl peroxide significantly reduced the number of acne lesions compared to the placebo. This reduction in lesions has allowed for a decrease in the risk of atrophic scarring. Indeed, by week 24, 32.9% of the treated areas showed little or almost no scarring, compared to 16.4% for the placebo.

Following these studies, the combined use of benzoyl peroxide and adapalene appears to play a role in the prevention of scarring and could also lessen those already formed. From a mechanistic perspective, adapalene is a retinoid that stimulates collagen production, promotes exfoliation, and reduces inflammation, while benzoyl peroxide targets the bacteria responsible for acne and exfoliates the skin.

Although study results have shown some effectiveness of the benzoyl peroxide/adapalene combination in reducing acne scars, it is advisable to consult a dermatologist or a healthcare professional before using products containing these active ingredients.

Indeed, this commonly used combination requires certain precautions due to its potential side effects. Benzoyl peroxide and adapalene should particularly be avoided on skin that is fragile, eczematous, or sunburned as they can cause skin dryness or inflammatory reactions, such as erythema or contact dermatitis. Furthermore, the use of this combination of active ingredients is not recommended for pregnant women and children under 12 years of age.

Furthermore, it is crucial to avoid applying these active ingredients on sensitive areas, such as the eye contour, nose, around the mouth and mucous membranes as this could lead to severe irritations. They can also increase the skin's sensitivity to UV rays, hence the need to use a sunscreen in the morning to reduce the risks of phototoxicity and skin irritation. Lastly, benzoyl peroxide should not come into contact with clothing and hair as it poses risks of discolouration and bleaching.

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• MEYER K. & et al. Safety and efficacy of a fixed-dose combination of adapalene 0.1% and benzoyl peroxide 2.5% gel in the treatment of acne vulgaris. Journal of Dermatological Treatment (2015).

• GALDERMA. New data from the phase 4 OSCAR trial demonstrated that Epiduo® Forte (adapalene and benzoyl peroxide) gel, 0.3%/2.5% reduced acne lesions, thereby lowering the risk of scarring in patients with moderate-to-severe acne (2018).

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