Which cosmetic ingredients should be avoided in summer?

During the summer period, the selection of your cosmetics should be meticulous. Indeed, certain ingredients and/or cosmetic actives are irritating, photosensitising and allergenic.

Note : A molecule is said to be photosensitising when it increases the skin's sensitivity to the sun.

Exposure to the sun before or after the use of these ingredients and/or actives can exacerbate these skin reactions. Furthermore, when irritated skin is exposed to the sun, brown spots may appear.

Some active substances and/or ingredients are to be avoided or used with caution during the summer:

• The retinol.

  Retinol is a derivative of Vitamin A, belonging to the family of retinoids. It is known for its keratolytic properties. Indeed, it works at the dermis level, stimulating the synthesis of collagen, elastin and hyaluronic acid. Therefore, it is one of the most effective ingredients for combating signs of ageing.

  Retinol, along with other molecules from the retinoid family, are photosensitising, meaning they increase the skin's sensitivity to the sun. Indeed, due to its keratolytic action, retinol thins the epidermis, making it more susceptible to UV rays.

Note : Studies have proven that the use of retinyl palmitate (a retinol ester) followed by or preceded by sun exposure damages DNA and proteins, leading to an increased risk of tumours.

• The alpha-hydroxy acids (AHA).

  The AHA (glycolic acid, lactic acid, mandelic acid...) are renowned for their keratolytic properties: they eliminate dead cells on the surface of the epidermis, promoting skin renewal. These are essential actives for blemished skin and dull skin. However, AHAs are photosensitising and can be irritating.

• The essential oils.

  Essential oils are aromatic extracts derived from plants. They are highly regarded in cosmetics due to their numerous benefits. However, even though they are natural, they are not without risks.

  Some essential oils may contain photosensitising chemical substances : the furocoumarins. Furthermore, essential oils contain potentially allergenic substances.

The ingredients and/or actives mentioned above are therefore to be avoided during sunny periods. However, if you wish to continue using them, it is important to adopt certain good practices :

• Apply these only in the evening to avoid the risk of photosensitisation, irritation and burns.

• In the morning, always apply a broad-spectrum UVA/UVB protection suitable for your skin type in a sufficient quantity. Reapply every 2 hours.

• Avoid exposing yourself to the sun between 10 am and 4 pm, a period during which UV rays are at their most intense

• Adopt protective clothing : covering clothes, cap, sunglasses.

• PETER P. F. U. & al. Photodecomposition and phototoxicity of natural retinoids (2005).

• SHARAD J. & al. Glycolic acid peel therapy – a current review (2013).

• FARRAR F. C. & al. Clinical Aromatherapy (2020).