Bakuchiol, an active ingredient to avoid during sun exposure?

A photosensitizing molecule is a substance that increases or alters skin sensitivity to light, in particular UV rays.

Two types of photosensitizing molecules are distinguished: photoallergic and phototoxic substances. After light exposure, photoallergic substances trigger an immune response that causes an allergic reaction, manifesting as an eczema-like reaction, with irritation, redness, and flaking. These adverse effects appear after a sensitization phase and can affect areas exposed or not to sunlight.

Phototoxic substances cause immediate damage after sun exposure. Their interaction with light produces reactive oxygen species, which damage DNA, lipids, and proteins in skin cells, leading to redness, burning sensations, and hyperpigmentation in some cases. The reaction from a phototoxic molecule is limited to areas exposed to UV rays but can increase the risk of skin cancer.

The bakuchiol is an active ingredient recognized for its multiple skin benefits. It smooths wrinkles, improves skin firmness, evens skin tone, reduces blemishes, soothes inflammation, and supports the healing process, while demonstrating an excellent tolerance profile, even on sensitive skin. Often described as a plant-based alternative to retinol, the bakuchiol shares certain effects and mechanisms of action and can stimulate collagen synthesis by dermal fibroblasts. This similarity is partly due to their chemical structures, which, while not identical, are closely related.

This common comparison with retinol may cause confusion because the retinoids are known to be photosensitizing and require extra caution during sun exposure.

However, current studies indicate that the purified bakuchiol is not photosensitizing. Photosensitization risks are associated with crude extracts of Psoralea corylifolia, the source plant of bakuchiol, because these extracts may contain psoralens and furocoumarins, compounds with known phototoxicity. These molecules increase skin sensitivity to the sun by absorbing UVA rays, making them photoreactive. Once activated by light, they form covalent bonds with DNA and cellular proteins, producing reactive oxygen species that damage skin cells and cause redness and warmth.

However, the bakuchiol used in skincare is obtained through purification processes, including liquid-liquid extractions and chromatography steps that remove photosensitizing molecules and retain only bakuchiol. Clinical studies on bakuchiol confirm its good tolerance: no photosensitization reaction was reported after using a formulation containing this molecule.

The bakuchiol is an active ingredient that can be used in the morning and/or evening, depending on preference.

However, although bakuchiol does not pose a photosensitization risk, we recommend that you protect your skin with daily sunscreen use. Sunscreen use is essential to prevent cellular damage that increases the risk of skin cancers, as well as the photoaging, regardless of the actives used.

• JOHNSON B. E. & al. Photosensitivity due to retinoids: Clinical and laboratory studies. British Journal of Dermatology (1986).

• MARCHIO F. & al. Bakuchiol in the management of acne-affected skin. Cosmetics & Toiletries (2011).

• SODHA P. & al. The use of bakuchiol in dermatology: A review of in vitro and in vivo evidence. Journal of Drugs in Dermatology (2022).

• SIVAMANI R. K. & al. Finding the right bakuchiol: Choose wisely. Journal of Cosmetic Dermatology (2023).