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Alpha hydroxy acid (Acne)

Alpha hydroxy acids (often referred AHAs), are a class of compounds, that may be either naturally occurring or synthetic. The most commonly used AHAs are glycolic acid and lactic acid1. They are thought to work by reducing inflammation and remove dead skin cells by disrupting the structures holding the skin cells together2. This ‘comedolytic’ or peeling effect is beneficial in acne, where clogging of the pores with dead skin cells among other mechanisms lead to formation of blackheads/whiteheads and pimples. AHAs are also referred ‘chemical exfoliators’. Furthermore, hydroxy acids stimulate the growth of smooth skin and thereby make the pores look smaller and reduce scars.

Level of evidence: A

The use of cleansing products containing AHAs have been shown to benefit people with acne. A study reported that a cleansing product with a pH of 4 containing glycolic acid, improved mild acne when applying it twice daily for 6 weeks compared to before treatment3. Another study based on 120 patients showed a significant positive effect after 45 days when using 10% glycolic acid as a the only treatment. All patients in the study had an effect which was significantly different from the control group using products without alpha hydroxy acids4.

Furthermore, a recent study showed an effect when using products containing glycolic acids as part of a 3 step acne treatment routine (combined with other active ingredients such as benzoyl peroxide). After 6 weeks of use 90% of the acne patients with mild-to-moderate acne (between 12-35 years old) experienced positive effects on their acne5.

When you use products containing AHAs, you should be aware of the sun. Research shows enhanced sensitivity to UVB radiation after using a topical solution with 10% glycolic acid for 6 weeks, but also that this increased sensitivity reverses within a week after the treatment is terminated6.

The concentration of an ingredient is important for its efficacy, and therefore products containing the same ingredient may not necessarily have the same effect as in the studies mentioned above.

Updated: July 2017


1Int J Cosmet Sci. 2015

2Clin Cosmet Investig Dermatol. 2013

3J Cosmet Dermatol. 2014

4J Cosmet Dermatol. 2011

5Clin Cosmet Investig Dermatol. 2017

6Photodermatol Photoimmunol Photomed. 2003

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