What are the dangers of glycolic acid?

Often used in peelings, glycolic acid is a fruit acid known for its exfoliating virtues. Indeed, it has the ability to detach dead skin on the surface and thus stimulate the renewal of epidermal cells. Glycolic acid is present in many cosmetic product formulas at a concentration between 4 and 10%: serum, cream, tonic lotion, shower gel, etc... However, although it is suitable for almost all types of skin (normal, combination to oily and mature), glycolic acid can sometimes be poorly tolerated. The effects of this active ingredient are very variable and depend on the concentration of glycolic acid, the pH of the product and the application time. That's why it's important to always read the instructions carefully before any application.

Thus, it is likely and normal to experience slight tingling and a mild warming sensation, and to see redness appear following the application of cosmetics containing glycolic acid. However, depending on your skin's tolerance level, these symptoms may intensify and may even be accompanied by erythema, burning sensations, tightness, itching, and facial swelling, and hyperpigmentation. In rare cases, hypopigmentation, persistent erythema, and a breakout of spots have been reported. As soon as such side effects appear, immediately stop using the product and consider rinsing your face thoroughly with water. However, at Typology, we advise against its use onsensitive and reactive skin, as well as for individuals suffering from an inflammatory skin condition (eczema, rosacea, herpes, etc…). It is also advisable to avoid using it in pregnant women. Indeed, it is the cause of vascular disorders related to hormonal impregnation, resulting in congestive outbreaks on the face: the skin reddens more easily and becomes more sensitive.

Like other fruit acids found in most facial care products, glycolic acid does not mix well with the sun. Indeed, it can increase the skin's sensitivity to the sun's UV rays and raise the risk of sunburn even without direct sun exposure. Due to its exfoliating power, the skin is left without its natural protection against the sun's rays until the complete reformation of the stratum corneum and the hydrolipidic film. Indeed, the stratum corneum helps to protect the dermis by absorbing or reflecting UV rays, particularly UVB rays. However, by thinning this protective layer, we expose our epidermis to cellular damage: the skin begins to redden under the effect of UV rays. That's why it's better to apply your glycolic acid treatments in the evening, especially since our cell renewal process is more active during the night. If you're using glycolic acid-based products, make sure to properly hydrate your skin with a moisturising face cream suitable for your skin type, to restore the hydrolipidic film. Furthermore, remember to protect your skin from the sun by applying a SPF30 type photoprotection in the morning.

Furthermore, to avoid any adverse effects, it is recommended to perform a sensitivity test in the crook of your elbow for 48 hours prior to using the product on your face, and also to avoid applying it around the eye area. If your skin begins to sting and/or redden, reduce the acid concentration and/or space out the applications. For instance, you could start by using a product with a low glycolic acid concentration and limit applications to once a week in the case of highly concentrated treatments, allowing your skin to acclimatise to the active ingredient and observe how your skin reacts. Subsequently, you can gradually increase the frequency of application and the concentration over time.

It is important to note that the combination of glycolic acid with other cosmetic actives can be irritating. This is particularly the case with the combination of glycolic acid and those based onretinoic acid (vitamin A). Although this combination has shown interesting results on the skin, it is not recommended for dry and sensitive skin types that may not tolerate it well due to its strong effect, especially if your skin is not accustomed to retinol.

The same applies tosalicylic acid (B.H.A.). In particular, care must be taken with the overall concentration of keratolytic ingredients. We therefore advise you to consult your dermatologist beforehand, who will be able to guide you best and find the right dosage according to your skin and your needs. However, salicylic acid and glycolic acid can be effectively combined as targeted treatments against acne.

Similarly, we advise against combiningglycolic acid with alkalising actives such as vitamin C. Indeed, for optimal effectiveness, glycolic acid should be in formulas with a slightly acidic pH (between 3 and 5.5), and vitamin C, for instance, will lose its effectiveness in this combination. Likewise, thecombination of glycolic acid with clay masks is incompatible. Indeed, incorporating it with clay, which is rather alkaline in nature, while glycolic acid is an acidic active, is not recommended and will have consequences on its effectiveness. Also, avoid using vitamin B3 with glycolic acid. The same observation applies, vitamin B3 requires a neutral pH to function effectively, while glycolic acid has a low pH.

• KORNHAUSERA. & al. Topical application of glycolic acid intensifies photodamage caused by ultraviolet light. Photodermatology, Photoimmunology and Photomedicine (2003).

• HEARING V. J. & co. The impacts of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced redness, DNA damage and sunburn cell formation in human skin. Journal of Dermatological Science (2009).