Salicylic Acid is a beta-hydroxy acid derived from willow bark, wintergreen leaves, and sweet birch that is commonly known within the skincare industry for its ability to assist with acne, acne-scarring, hyperpigmentation, and skin texture.1 It is most frequently associated within dermatology for its exfoliating effects on the skin and its use as an anti-inflammatory (serving as the main ingredient in aspirin).
Salicylic Acid is one of the predominant skincare ingredients used within the composition of cosmetic exfoliants and acne treatments. It falls into the beta-hydroxy acid group, which is a less-intensive form of acid compared to most of the other acids used for dermatological treatments of the skin -- referred to as alpha-hydroxy acids; however, due to its penetrative and lipophilic (it can bypass fatty or oily barriers in cells) nature, it is recognized for its ability to quickly enter the epidermis (and works to restore active acne lesions).2
The use of Salicylic Acid functions through a restructuring process where it resurfaces the skin and stimulates the production of collagen and elastin in the dermis.2 The intercellular oils that normally prevent the entrance of acids to skin cells are dissolved when Salicylic Acid is applied.3
The controlled destruction of epidermal cells allow Salicylic Acid to assist with a decrease in follicular openings which, when infected with bacteria, become known as acne.2 This restructuration is what allows Salicylic Acid such efficacy in removing oil from pores, dissolving pigment, and smoothing scarred areas.
Another purpose of Salicylic Acid is in its long-standing use as an anti-inflammatory, having been recorded as prescribed by Hippocrates back in third century BC.4 Inflammation can be induced by the immune system and requires the creation of certain proteins, which act to mobilize inflammatory cells to damaged areas of the body. Salicylic Acid works by inhibiting those proteins from forming by binding itself to them during development.4
Salicylic Acid is known for its use in the treatment of multiple types of acne, but specifically in its removal of comedones (blackheads) due to its ability to penetrate and remove excess oil or dead skin within the pores. Through that same penetrating mechanism, it also helps to reduce oily skin and enlarged pores that are more likely to become blackheads.5
Salicylic Acid’s effect as an anti-inflammatory and its ability to resurface the skin makes it a common ingredient for addressing post-inflammatory hyperpigmentation (PIH) and other major skin-texture issues, such as melasma, which result from inflammation.5 Observable melanin content of the skin is reduced when Salicylic Acid is applied due to the resurfacing effect, and malignant melanocytes (skin-cells responsible for pigment) are destroyed.2 As inflammation can also be responsible for uneven pigment, the application of Salicylic Acid also serves as an effective preventative measure for those who may suffer from future issues with PIH.3
The primary benefits of Salicylic Acid are found in its overall effects for all types of skin health. With anti-inflammatory effects, the ability to reduce and prevent blackheads, the restoration of collagen and elasticity in the skin, and the capacity to provide an even skin tone and texture, Salicylic Acid’s employment is well justified for treating a variety of skin disorders.
It is associated with very low side-effects or adverse reactions, and has an approval for use on all types of skin (due to a lack of post-inflammatory hyperpigmentation or scarring) -- following its use for exfoliation and the reduction of age and acne-related issues.3 While exfoliating, Salicylic Acid has also been clinically observed to not cause any other inflammatory response within the epidermis that would result in further issues post-application.5
Other benefits of Salicylic Acid include: its ability to only target inflammatory-cell production rather than also stopping the mobility of other necessary immune responses,4 the reduction of oily-skin and large pores due to its inhibition of follicular opening,2 and positive changes to pigment without resulting in over-pigmentation of the affected areas.3
The frequency of use for Salicylic Acid products is dependent on the level of concentration and the type of application. In the case of chemical peels (administered by professionals in a clinical environment), it was studied to be highly efficacious when applied fortnightly at a 30% concentration over a period of 12 weeks.2 Due to the differences in concentration that can be found amidst a wide variety of topical products, it is important to follow the specific application instructions of anything containing Salicylic Acid.
The results for Salicylic Acid have been studied extensively on a variety of skin conditions, but the overall effects of Salicylic Acid tend to improve or prevent multiple disorders simultaneously.
In regards to the treatment of acne, the use of Salicylic Acid has been observed to result in a significant decrease in the prevalence and recurrence of blackheads due to its exfoliation effect.2 Its ability to remove oil and dead cells from pores and/or follicles in the epidermis has been observed to reduce instances of oily-skin and prevent the formation of new blackheads or sources of bacterial infection that result in acne.2,5
The timeline for results of Salicylic Acid treatments can depend on the type of treatment used, and the condition it is treating; for facial lesions, acne-scarring, pigmentation, and other primary skin disorders, results have been observed to be visible within 4 weeks of application.2,3,5,6 When being used for chemical peeling, Salicylic Acid demonstrated significantly improved results for blackheads and other forms of acne within 1 week of application, and a full disappearance of blackheads by the 3 month point.5 Although, due to the number of different varieties of Salicylic Acid application, the effects are dependent on the product and condition of the skin.
Salicylic Acid has one of the longest histories of all skincare ingredients due to its lack of side-effects and adverse issues. When being used in intensive forms, such as chemical peeling, it has been observed to not have any inflammatory effects,5 and no participants of multiple studies were observed to have experienced any type of post-inflammatory hyperpigmentation, scarring, or allergic reactions following its application.1,2,3,5,6,7,8 Because of its lack of issues regarding post-treatment pigmentation or scarring issues, it is available to treat anyone of any pigment or colour3.
When used too intensely, or in extremely rare cases, it has been observed to cause moderate redness of the skin or dryness -- and thus a moisturizer and SPF protection have been recommended following exfoliation with Salicylic Acid to help prevent the likelihood of these effects.3
Glycolic Acid is another ingredient commonly used for exfoliation and assisting with acne, skin lesions, and pigmentary issues within the skin. The primary difference between Glycolic Acid and Salicylic Acid (when used to treat the same issues) is found in the inherent property of each acid: Glycolic Acid is hydrophilic, which prevents it from being able to penetrate the deeper fatty tissues that Salicylic Acid is able to due to its lipophilic nature.2 This lipophilic property allows Salicylic Acid a significant advantage in treating comedones and other noninflammatory lesions within the skin, as there is a layer of oil protecting the infected follicles.
Another significant result in comparative studies of Glycolic and Salicylic Acid was the long-term effectiveness of each. While both acids demonstrated a significant reduction of acne scars, Glycolic Acid was observed to have new instances of acne lesions following the discontinuation of regular application, whereas Salicylic Acid was seen to continuously show results up to 2 months after the last peel.10
1. Jha, A., Siddalingappa, K., Herakal, K., Malhotra, K., & Gowda, H. (2018). COMPARATIVE EFFICACY OF 35% GLYCOLIC ACID PEEL VS. 20% SALICYLIC ACID PEEL IN THE TREATMENT OF POST ACNE SCARRING. JOURNAL OF EVOLUTION OF MEDICAL AND DENTAL SCIENCES-JEMDS, 7(19), 2426-2428.
2. Garg, V. K., Sinha, S., & Sarkar, R. (2009). Glycolic acid peels versus salicylic–mandelic acid peels in active acne vulgaris and post‐acne scarring and hyperpigmentation: a comparative study. Dermatologic Surgery, 35(1), 59-65.
3. Fabbrocini, G., Annunziata, M. C., D'arco, V., De Vita, V., Lodi, G., Mauriello, M. C., ... & Monfrecola, G. (2010). Acne scars: pathogenesis, classification and treatment. Dermatology research and practice, 2010.
4. Choi, H. W., Tian, M., Song, F., Venereau, E., Preti, A., Park, S. W., ... & Agresti, A. (2015). Aspirin’s active metabolite salicylic acid targets high mobility group box 1 to modulate inflammatory responses. Molecular medicine, 21(1), 526-535.
5. Dainichi, T., Ueda, S., Imayama, S., & Furue, M. (2008). Excellent clinical results with a new preparation for chemical peeling in acne: 30% salicylic acid in polyethylene glycol vehicle. Dermatologic Surgery, 34(7), 891-899..
6. Vakirlis, E., Theodosiou, G., Lallas, A., Apalla, Z., & Sotiriou, E. (2019). Terra firma‐forme dermatosis: Differential diagnosis and response to salicylic acid therapy. Pediatric dermatology.
7. Rathod, D., Pandya, P., Pandya, I., Shah, G., Shah, R., & Padhiyar, B. (2018). Comparison of efficacy of commercially available vs. freshly prepared salicylic acid peel in treatment of acne: a randomized open-label study. Biomedical Dermatology, 2(1), 25.
8. Strauss, J. S., Krowchuk, D. P., Leyden, J. J., Lucky, A. W., Shalita, A. R., Siegfried, E. C., ... & Bhushan, R. (2007). Guidelines of care for acne vulgaris management. Journal of the American Academy of Dermatology, 56(4), 651-663.
9. Alexis, A. F., Harper, J. C., & Tan, J. K. (2018). Acne and Rosacea: Applying Emerging Science to Improve Outcomes. L. F. S. Gold (Ed.). Frontline Medical Communications Incorporated.
10. Kempiak, S. J., & Uebelhoer, N. (2008, September). Superficial chemical peels and microdermabrasion for acne vulgaris. In Seminars in cutaneous medicine and surgery (Vol. 27, No. 3, pp. 212-220). No longer published by Elsevier.
11. Seidler, E. M., & Kimball, A. B. (2010). Meta-analysis comparing efficacy of benzoyl peroxide, clindamycin, benzoyl peroxide with salicylic acid, and combination benzoyl peroxide/clindamycin in acne. Journal of the American Academy of Dermatology, 63(1), 52-62.