Skincare Ingredients Not To Mix.

Beta-hydroxy acids (BHAs) and alpha-hydroxy acids (AHAs):

These compounds have the same mechanism of action: they eliminate dead cells from the stratum corneum. The most common AHAs are glycolic acid and lactic acid, while the best-known BHA is salicylic acid. Used together, AHAs and BHAs lead to immoderate exfoliation of the epidermis, which can cause irritation and compromise the skin barrier.

Salicylic acid and vitamin C:

To bring radiance and luminosity to a dull, tired complexions, you can combine vitamin C and salicylic acid in your daily beauty routine, but be careful not to use them at the same time. Salicylic acid is photosensitizing and is best applied in the evening, while vitamin C can be used in the morning to protect the skin from free radicals generated during the day.

Salicylic acid and azelaic acid:

Azelaic acid is an antioxidant and antibacterial agent that deeply cleanses clogged pores. Its action is very similar to that of salicylic acid. Combined, these two acids can lead to overly aggressive exfoliation, causing redness and irritation. Thus, both are skincare ingredients not to mix, and we strongly advise against combining them in your beauty routine.

Retinol and benzoyl peroxide:

What not to use with retinol? Benzoyl peroxide, for instance. It is an active ingredient recommended for the treatment of blemishes. It regulates sebum production and inhibits the proliferation of the bacteria responsible for acne, Propionibacterium acnes. It is not recommended to combine these two active ingredients at the same time during a skincare routine, as benzoyl peroxide can oxidize retinol, making it much less effective in the fight against skin aging. Furthermore, combined, these two substances can cause irritation and over-dry the epidermis. As benzoyl peroxide and retinol are both photosensitizing (i.e., they increase the skin's sensitivity to the sun's UV rays), they are best used in the evening. We recommend alternating these two active ingredients every other evening, to benefit from their respective effects without combining them at the same time.

Vitamin C and glycolic acid:

Used at the same time, glycolic acid and vitamin C can dry out your skin and even cause pigmentation spots. When applied to the skin, use a vitamin C product in the morning and a glycolic acid product in the evening.

Vitamin C and retinol:

Vitamin C is recognized for its action on pigmentation spots and its brightening power on dull, tired complexions. In the literature, it has been shown that these two active ingredients in the same skincare product can significantly slow down the skin's aging process. Nevertheless, both substances can be potentially irritating, and we do recommend that vitamin C is rather not to be used with retinol on sensitive and atopic skin. To reap the benefits of these two active ingredients, use a vitamin C-based skincare product in the morning to help the skin fight free radicals, generated throughout the day by factors such as the sun and pollution. In the evening, use a retinol treatment for its tightening and plumping properties.

Retinol and AHA:

Vitamin A, also known as retinol, has an exfoliating action when applied to the skin. AHAs have the same properties, and are often used in exfoliating skincare products. This combination is particularly aggressive for sensitive skin. Nevertheless, it should be pointed out that glycolic acid, combined with retinoic acid, the active form of vitamin A, has been shown to be more effective in reducing imperfections.

Dihydroxyacetone (DHA) and peptides:

Dihydroxyacetone is an active ingredient found in self-tanning products. When DHA comes into contact with skin proteins, it provokes a chemical reaction that triggers a superficial brown tint. Combining a self-tanner with a peptide-rich skincare product is not dangerous, but it can alter the effects of the self-tanner. In fact, DHAmay react preferentially with peptidesrather than epidermal proteins.