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Dangers de l'utilisation de l'acide lactique en cosmétique.

Dangers and Side Effects of Lactic Acid Products.

Lactic acid is a compound often found in a peel, cream, or serum, appreciated for its keratolytic properties. Moreover, it has the particularity to be particularly soft for the skin. However, there are a few precautions to take when using a lactic acid product. Discover the side effects of this compound.

Lactic Acid: Possible Side Effects.

acids. It is frequently used in lactic acid peels because it has excellent keratolytic properties, i.e., it eliminates dead cells on the surface of the epidermis.

In fact, a lactic acid peel dissolves the intercellular bonds. By stimulating cell renewal, it revives dull complexions and prevents the appearance of imperfections (pimples, blackheads…). Compared to glycolic acid, lactic acid is better tolerated because it has a higher molecular weight allowing it to remain on the surface of the epidermis and to be less irritating.

However, although it is suitable for all skin types, lactic acid remains a powerful active ingredient that can cause side effects:

  • An increase in sensitivity to the sun: Like all molecules in the AH. family, lactic acid is photosensitizing, meaning that it increases the skin's sensitivity to the sun. Thus, the application of lactic acid products followed by a UV exposure can generate sun burn or cutaneous irritations;

  • Irritation: Although milder than glycolic acid, lactic acid is still an acid. It can cause light to moderate burning sensations that are temporary. These effects are rare, however, because at a concentration of 10% or less (the concentration of lactic acid authorized in cosmetics), the use of lactic acid is safe.

What Precautions Should Be Taken?

Like other fruit acids, lactic acid products do not mix well with the sun. In fact, they increase the skin's sensitivity to the sun's UV rays and increase the risk of sunburn, even without direct exposure. Because of the exfoliating power, the skin is deprived of its natural protection against the sun's rays until the stratum corneum and the hydrolipidic film are completely reformed.

The stratum corneum protects 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 starts to redden under the effect of UV rays. That's why it's best to apply your lactic acid product in the evening, especially since our cell renewal process is more important at night. The days following the application, remember to protect your skin from the sun by applying a broad spectrum sun protection.

In addition, to avoid any undesirable effects, perform a skin tolerance test. Put a few drops of your lactic acid peel, cream, or serum on the arm or the back of your hand and wait 24 hours. If your skin starts to sting or redden, reduce the acid concentration or space out the applications. Thereafter, you can gradually increase the frequency of application and the concentration.

What Other Ingredients Not To Combine With Lactic Acid.

  • AHA and BHA: As a precautionary principle, we advise against the simultaneous use of lactic acid with other fruit acids, such as glycolic acid and salicylic acid. Indeed, the application of too high a concentration of keratolytic active ingredients may sensitize the skin;

  • Retinol: This molecule is photosensitizing and “powerful”. Moreover, it is a keratolytic agent. Thus, it is not recommended to combine lactic acid and retinol because it could irritate the skin, especially for people with sensitive skin;

  • Vitamin C: It is not recommended to combine vitamin C with strong acids such as lactic acid. This mixture may cause irritation and inflammation of the epidermis. However, it is possible to apply your lactic acid product in the evening and your vitamin C product in the morning.

Sources

  • SMITH W. P. & al. Epidermal and dermal effects of topical lactic acid. Journal of the American Academy of Dermatology (1996).

  • BERGFELD W. F. Cosmetic use of alpha-hydroxy acids. Current drug therapy (1997)

  • ROTSZTEJN H. & al. Lactic and lactobionic acids as typically moisturizing compounds. International Journal of Dermatology (2018).

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