"AHAs are generally recognised as safe; however, due to their exfoliating properties, they can cause specific side effects, including mild skin irritation, redness and a tingling sensation upon application. These side effects are generally temporary, however, and tend to subside with continued use of AHAs or by adjusting their concentration or frequency of application.
It is important to understand the underlying mechanism of these side effects. Indeed, the exfoliation process, which promotes the removal of dead skin cells, disrupts the skin's barrier function, leading to increased transepidermal water loss and, consequently, heightened sensitivity. It also leads to a thinning of the stratum corneum, thereby reducing its ability to provide a natural barrier against UV rays. Consequently, the skin becomes more sensitive to the sun. It is therefore essential to use sunscreen and avoid sun exposure while using AHAs, and even for up to a week after the last application.
A gradual approach using lower concentrations of AHAs is particularly beneficial for people with sensitive or reactive skin. This method allows the skin to acclimate gradually, thereby reducing the risk of adverse reactions. Additionally, formulating AHA-based products at a lower pH can enhance their efficacy while minimising skin irritation. By adjusting the pH, the exfoliating properties of AHAs can be maintained while minimising their potential to disrupt the skin barrier and cause irritation.
Incorporating soothing and moisturising ingredients alongside AHAs can further improve the tolerability of topical formulations and strengthen the skin barrier function."
