What are the dangers of PHAs?

The P.H.A.s (Polyhydroxy Acids) are part of the hydroxy acid family along with A.H.A.s (Alpha Hydroxy Acids) and B.H.A.s (Beta Hydroxy Acids). Considered as the new generation of A.H.A.s, they are renowned for their keratolytic effects, meaning they remove dead cells (a process known as desquamation), which boosts cell renewal and restores radiance to the skin. Moreover, this desquamation allows for deep pore cleansing, thus limiting the appearance of imperfections.

They also possessmoisturising and humectant properties.This is due to the numerous hydroxyl functions they contain (OH-) at the level of their chemical structures. These capture water molecules and prevent transepidermal dehydration, thus strengthening the skin barrier.

Among the acids included in P.H.A.s, three are primarily used in cosmetics:

• The gluconolactone: This is a P.H.A. naturally present in skin cells. This antioxidant effectively combats free radicals.

• Galactose: It is also naturally present in the body. Its role is to stimulate the production of collagen.

• Lactobionic Acid : This is a derivative of lactose that has a moisturising and soothing effect.

Unlike A.H.A. and B.H.A., P.H.A. are suitable for all skin types, even those that are sensitive. Indeed, due to their high molecular weights, they remain on the surface of the epidermis. This explains their good skin tolerance compared to other acids which penetrate more deeply into the epidermis.

There is no contraindication to the use of P.H.A. They can be applied to all skin types, even the most reactive and sensitive ones.

However, as this is an acid, we advise you to perform a skin tolerance test before using this active ingredient daily. To do this, apply a few drops of the product to the crook of your arm and wait 24 hours. If you observe no reaction, you can apply the treatment to your face.

Finally, P.H.A.s do not present any contraindications to sun exposure, unlike A.H.A.s which are photosensitising.

Please note : A molecule is photosensitising when it increases the skin's sensitivity to UV rays.

• HEARING V. J. & al., Applications of hydroxy acids: classification, mechanisms, and photoactivity.Clinical,Cosmetic and Investigational Dermatology (2010).