Wrinkles: The virtues of glycolic acid on the skin?

As we age, the skin undergoes changes, leading to the emergence of wrinkles among other things. This happens as the collagen and elastin fibres in the dermis decrease, the levels of glycosaminoglycans such as hyaluronic acid diminish, and the subcutaneous fat atrophies. Interestingly, superficial chemical peels with glycolic acid have been found to be effective on fine wrinkles due to their unique properties, in addition to their benefits on xeroderma, ichthyosis, acne, and hyperpigmentation disorders (melasma, lentigines, etc.). Studies have reported that the topical application of glycolic acid results in a clinical improvement of ageing skin and associated histological changes.

The clinical and histological data available to date indicate that the topical application of glycolic acid, at all concentrations, is effective in the treatment of mild wrinkles. Controlled clinical trials have histologically demonstrated an increase in the thickness of the epidermis showing moderate to severe photoaging after an average treatment period of 6 months (twice a day) with a 25% glycolic acid lotion and a pH of 3.5. Other structural changes are also apparent, including changes in elastin fibres, epidermal and dermal levels of glycosaminoglycans, and dermal collagen levels, with more pronounced effects at the highest concentrations of glycolic acid.

Despite their benefits, superficial glycolic acid peels cannot eradicate severe and deep wrinkles. These serious skin flaws must be treated with other surgical procedures (deep chemical peels, skin resurfacing lasers, etc.).

By what mechanism?

Theglycolic acid revitalises the skin from multiple angles at once, due to its ability to penetrate the skin, to reduce the visibility of wrinkles and fine lines, which are not limited to the skin's surface alone.

• Glycolic acid has the ability toinduce peeling of the outermost layers of the epidermis. It has been shown to cause the progressive loosening of corneocytes and, at high concentrations, the detachment and destruction of the epidermis (epidermolysis). By removing the top layer of dead skin cells, it improves the appearance of the skin and reduces the visibility of wrinkles.

• Glycolic acid mediates in addition a speeding up of the epidermal renewal. It has been demonstrated that it is capable of stimulating the basal proliferation of keratinocytes. This then results in an increase in the thickness of the epidermis after long-term use of glycolic acid.

• Glycolic acid also has direct effects on the stimulation of dermal connective tissue components, such as collagen and elastin, achieved through the proliferation and functional activation of dermal fibroblasts independent of inflammatory mechanisms, improving the biomechanical quality of the skin. However, this effect largely depends on the concentration. Thus, the use of high concentrations facilitates the penetration of glycolic acid into the dermis.

• Finally, glycolic acid increases the levels of hyaluronic acid in the epidermis and dermis in order tohelp maintain skin hydration and provide the aqueous environment for cell migration, affecting the appearance of the skin and helping to make fine lines less visible.

Masks, gels, toners, cleansers... there are numerous glycolic acid-based products on the market that tend to have concentrations ranging up to 10% and a pH around 4. They make a good option for daily skin care. However, to reach the deeper layers of the epidermis and reduce the appearance of wrinkles, a higher concentration of glycolic acid can be used.

Therefore, professional peels are a good solution. They contain up to 70% glycolic acid and will give you better results more quickly. However, as these peels contain higher percentages of glycolic acid, they carry a greater risk of irritation.

Due to the risks you may be exposed to, this type of peeling with a high concentration of glycolic acid (> 30%) must be strictly supervised by a dermatologist and falls under the category of dermatological procedures.

How does a dermatological peel procedure take place?

1. Skin Preparation: Patients first receive a lotion based on 10 or 15% glycolic acid to use once a day at home for two weeks, which helps to thin the horny layer and increase the skin's tolerance to the active ingredient. On the day of the peel, the skin is usually cleaned with alcohol to remove debris, impurities and surface sebum, thus allowing better penetration of the acid. For deeper peels, acetone is used for a more thorough cleaning.

2. Patient Protection: After cleansing the face, the doctor safeguards the patient's eyes using goggles, as well as the hair. A painkiller or a sedative may also be administered if it's a deep chemical peel.

3. Application of the peel: The doctor spreads the glycolic acid solution at a concentration of 50 to 70%, starting with the cheek, then gradually in a clockwise direction across the entire face, including the chin, upper lip and nose, using a cotton ball or sponge. The peel is left on for between 3 to 7 minutes. The patient may be subjected to a series of four peels repeated every 3 to 4 weeks to achieve good results by producing additive effects. After a few minutes, a tingling and burning sensation occurs.

   The longer the duration of the peeling application on the skin, the deeper the active ingredient will penetrate.

4. Removal of the chemical peel: To remove the peeling agent, it is crucial to start in the same direction as when it was applied. Several gauzes soaked in water are gently passed over the patient's face to remove the majority of the glycolic acid and dilute the remaining acid. Often, a gentle facial cleansing lotion is applied to further neutralise and soothe the skin. The patient is then advised to gently splash water on their skin over the sink until the tingling sensation has subsided.

5. Post-peeling care: Following the peeling session, a hydrating sunscreen is applied. Additionally, an antibiotic ointment and a hydrocortisone-based ointment are recommended for the initial days. During the recovery period of approximately one to two weeks, the skin will be likely red, swollen and flaky. During this phase, any exposure to the sun should be limited. Antiviral medications can be taken.

However, glycolic acid chemical peels are contraindicated in individuals with recurrent facial herpes lesions or those taking oral retinoids, which can impair healing after the peel. It is necessary to wait at least 6 months after discontinuing the oral retinoid before considering proceeding with a superficial chemical peel.

• MOY R. L. & al. Glycolic acid peels for the treatment of wrinkles and photoaging. Journal of Dermatologic Surgery and Oncology (1993).

• SPEELMAN P. & al. A histological comparison of 50% and 70% glycolic acid peels using solutions with various pHs. Dermatologic Surgery (1996).

• VAN SCOTT E. J. & al. Effects of alpha-hydroxy acids on photoaged skin: a pilot clinical, histologic, and ultrastructural study. Journal of the American Academy of Dermatology (1996).

• MAIBACH H. I. & al. Increased in vivo collagen synthesis and in vitro cell proliferative effect of glycolic acid. Dermatologic Surgery (1998).

• YOUN J. I. & al. The effect of glycolic acid on photoaged albino hairless mouse skin. Dermatologic Surgery (1999).

• ICHIHASHI M. & al. The efficacy of glycolic acid for treating wrinkles: analysis using newly developed facial imaging systems equipped with fluorescent illumination. Journal of Dermatological Science (2001).

• FABBROCINI G. & al. Glycolic acid adjusted to pH 4 stimulates collagen production and epidermal renewal without affecting levels of proinflammatory TNF-α in human skin explants. Journal of Cosmetic Dermatology (2020).