Glycolic Acid: Which active ingredients should it not be combined with?

Even though some combinations of active ingredients are beneficial for the skin, others are less so as they can trigger certain skin reactions, especially in individuals with sensitive or atopic skin. Here are some combinations to avoid during your beauty routine.

• Glycolic acid and other exfoliating acids such as salicylic acid or lactic acid.

  These active ingredients work in the same way as salicylic acid: they eliminate dead cells from the stratum corneum. Used together, they can lead to a excessive exfoliation of the epidermis compromising the skin barrier. Therefore, they are excellent ingredients to use separately, but mixing them could cause a skin reaction (dryness, irritation, redness), particularly if they are used on very dry and sensitive skin.

  However, it is important to add some nuance to this discussion. The combination of A.H.A.s (such as glycolic and lactic acids) or A.H.A.s and B.H.A.s (like glycolic and salicylic acids) can be beneficial, particularly for alleviating acne breakouts. Moreover, in addition to their shared exfoliating properties, some molecules offer other benefits. For instance, lactic acid not only exfoliates but also has moisturising and soothing properties. Furthermore, the mode of action of A.H.A.s also varies depending on their size. Lactic acid, due to its molecular weight, acts on the surface, while the smaller glycolic acid penetrates more deeply, stimulating the synthesis of collagen, elastin and hyaluronic acid fibres. Therefore, combining exfoliating acids allows for a complementary action and greater effectiveness.

  Note : Regarding our A.H.A. based serums, these are too highly concentrated to be combined with each other. However, it is possible to find multiple A.H.A.s in the same cosmetic product on the market, in which case, the dosage will be adjusted accordingly.

• Glycolic acid and niacinamide.

  The layering of these ingredients is counterproductive. Indeed, niacinamide used with AHA's such as glycolic acid and lactic acid has no effect and can even cause redness. As niacinamide has a pH of around 5-7, it can actually increase the lower pH of glycolic acid, which is around 3-4, and negate its properties. This imbalance initially results in flushing and redness on the skin. Moreover, each ingredient interacts with the others, limiting the effectiveness of their absorption. Used separately, both ingredients can improve skin texture, acne, and signs of ageing, so we still encourage you to use them.

• Glycolic acid and retinol.

  A.H.A.s, of which glycolic acid is a member, are organic compounds known for their keratolytic properties. They allow for theexfoliation of the skin's surface and brighten dull complexions. When combined with retinoic acid, the active form of vitamin A, glycolic acid has shown increased effectiveness in reducing imperfections. However, both retinol and glycolic acid are substances that can dry out the epidermis and potentially cause redness and irritation, particularly in individuals with sensitive or atopic skin. Therefore, this combination should be avoided if you have sensitive skin.