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Dangers à l'utilisation des PHA.

What Are the Dangers or Side Effects of PHAs?

You may be asking yourself: What is PHA, and what are the risks and contraindications of PHA skin care? The PHAs (polyhydroxy acids) constitute a group of acid of the family of the hydroxylated acids. They are very appreciated for their keratolytic properties. Discover more in this article.

Published March 11, 2024, by Sandrine, Scientific Editor — 3 min read

What is PHA?

PHAs (polyhydroxy acids) are part of the family of hydroxy acids, along with AHAs (alpha-hydroxy acids) and BHAs (beta-hydroxy acids). Considered the new generation of AHAs, they are known for their keratolytic effects, i.e., they eliminate dead cells (desquamation process), which boosts cell renewal and restores the skin's radiance. Moreover, this desquamation allows unclogging the pores in depth thus limiting the appearance of imperfections.

They also have moisturizing and humectant properties. That is explained by the many functions of hydroxyls they contain (OH-) on the level of their chemical structures. These capture water molecules and prevent transepidermal dehydration, thus strengthening the skin barrier.

Among the acids included in the PHAs three are mainly used in cosmetic:

Gluconolactone: This is a PHA naturally present in skin cells. This antioxidant fights effectively against 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 moisturizing and soothing effect.

PHA – Mild Acids.

Unlike AHAs and BHAs, PHAs are suitable for all skin types, even sensitive skin. Indeed, because of their high molecular weight, 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 are no contraindications to the use of polyhydroxy acids. They can be applied to all skin types, even the most reactive and sensitive.

Nevertheless, as it is an acid, we advise you to carry out a skin tolerance test before using this active ingredient daily. To do so, apply a few drops of the product to the hollow of the arm and wait 24 hours. If you do not observe any reaction, you can apply the care to the face.

Finally, PHA skin care has no contraindication to sun exposure, unlike AHA which is photosensitizing.

Note: A molecule is photosensitizing when it increases the skin's sensitivity to UV rays.


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


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