Lactic Acid: With Which Active Ingredients Can It Be Combined?

Lactic acid is a postbiotic that is obtained by the fermentation of carbohydrates by microorganisms of the species Lactobacillus. Originally derived from milk, which is also where it got its name from. However, lactic acid is not only found in milk. It is also found in some fruits, vegetables, and wine. The use of lactic acid dates back to Ancient Egypt. Cleopatra liked to bathe in donkey milk, which contained large amounts of lactic acid, to keep her skin soft. Today, it is an ingredient in numerous cosmetics, such as cleansers, toners or serums. According to the European Cosmetics Regulation, a maximum concentration of 10% is allowed in a cosmetic product.

The interest in lactic acid is based on its exfoliating effect. Indeed, lactic acid is an alpha-hydroxy acid (A.H.A.). Like all acids of this family (glycolic acid, tartaric acid, citric acid...), lactic acid has keratolytic properties, i.e. it removes dead cells on the surface of the epidermis by dissolving the intercellular bonds. This accelerates skin renewal and combats the signs of aging (wrinkles, fine lines, blemishes) and skin impurities (blackheads, pimples, spots after acne). Compared to the other acids of the AHA family, lactic acid is particularly mild. This is due to its high molecular weight, which gives it an effect only on the surface, unlike other acids that enter deep into the epidermis. Therefore, lactic acid is an exfoliant suitable for all skin types, even sensitive skin.

The good tolerance of lactic acid is also due to the fact that it is a molecule that occurs naturally in the skin. In fact, thanks to its moisturizing properties, it prevents loss of water by retaining it in the epidermis. It is also part of the Natural Moisturizing Factor (NMF), which is responsible for improving the moisture content of the skin.

Note: The NMF or Natural Moisturizing Factor is made up of amino acids, their derivatives and extracellular compounds such as lactic acid. Its hygroscopic properties allow it to bind and retain water in the stratum corneum, thus maintaining skin hydration.

In high concentrations (over 10%), as used in medical peels, lactic acid has a depigmenting and brightening effect.

To make the most of the benefits of lactic acid, combinations with other active ingredients have been documented in the scientific literature.

Lactic acid can be combined with other active ingredients to maximize its effects. Lactic acid can be combined with:

• Ferulic Acid

Ferulic acid is an antioxidant active ingredient that fights cell oxidation, thus counteracting photoaging of the skin.

In a scientific study, the effectiveness of a peel containing a combination of lactic acid and ferulic acid was compared to a peel containing only ferulic acid. The results showed better efficacy of the peel with a combination of lactic acid and ferulic acid on fine wrinkles, photoaging and hyperpigmentation spots. Since lactic acid is a keratolytic agent, it refines the epidermis by removing dead skin cells. This leads to better absorption of ferulic acid into the skin, which multiplies its effect. Thus, lactic acid and ferulic acid act synergistically on photoaging.

In your beauty routine, on clean and dry skin, use our gentle exfoliating serum followed by our antioxidant serum with 3% ferulic acid. Because lactic acid is photosensitizing, this combination should only be used in the evening.

• Retinol

Retinol, a vitamin A derivative, is a powerful skin-firming ingredient that smoothes skin texture, reduces signs of aging, and effectively fights pigmentation spots as well as blemishes.

Lactic acid and retinol alleviate acne through their keratolytic action. A scientific study proves that the topical combination of A.H.A. (including lactic acid), retinol and B.H.A. (salicylic acid) significantly reduces inflammatory and non-inflammatory acne lesions after only 4 weeks. An improvement in overall skin quality was also observed. This combination is beneficial for skin with acne, but caution is advised against this combination for dry, sensitive or atopic skin.

In this study, the serum used was a combination of 0.1% of an AHA-retinol complex, 2% salicylic acid, and 10.04% lactic acid.

To benefit from the effects of lactic acid and retinol on acne, first use our mild exfoliating serum and then our retinol serum. Combining these two serums should only be done in the evening, as retinol and lactic acid are photosensitizing molecules.

However, retinol is a molecule that can be irritating and drying. If you have sensitive skin, you should opt for bakuchiol, which is a natural alternative to retinol with fewer side effects.

• The other acids

The combination of lactic acid, which is an AHA, with other acids such as BHA or PHA can be very interesting, as they complement each other in their effectiveness. Indeed, lactic acid acts on the surface of the epidermis by removing dead skin cells. Our exfoliating mask with 10% A.H.A. and 10% P.H.A. therefore helps to unclog pores while reducing the appearance of skin blemishes such as blackheads. Lactic acid also has moisturizing properties that improve the moisture content of the skin. Salicylic acid, thanks to its affinity for sebum, enters the pores of the skin and purifies them.

The combination of lactic acid and salicylic acid is therefore also beneficial for acne prone skin, as it provides a comprehensive effect against skin impurities.

Note: Our serum for local skin impurities contains 2% salicylic acid and our serum for gentle exfoliation was formulated on the basis of 10% lactic acid. In cosmetics, the combination of AHA+BHA cannot exceed 10%, so the combination of our two serums is not possible.

The combination of different AHAs with each other is also very beneficial. In addition to their common exfoliating properties, some molecules have other advantages. Lactic acid, for example, has moisturizing and soothing properties in addition to exfoliating properties. Furthermore, the mode of action of AHAs also differs depending on their size. Lactic acid works on the surface due to its molecular weight, while the smaller glycolic acid penetrates deeper and stimulates the synthesis of collagen fibers, elastin and hyaluronic acid.

When you combine the AHAs, they can complement each other's action for greater efficacy.

Note: Our AHA serums are too high dosed to be combined with each other. However, it is possible that several AHAs are contained in one cosmetic product, in which case the dosage will be adjusted.

Note: If you have sensitive or atopic skin, we do not recommend combinations between acids.