Bakuchiol, an active ingredient to avoid in sunlight?

A photosensitising molecule is a substance that increases or alters the skin’s sensitivity to light, particularly ultraviolet rays.

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

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

The bakuchiol is an active ingredient gaining attention for its many skin benefits. It helps smooth fine lines, improve firmness, even out skin tone, reduce blemishes, soothe inflammation and support the healing process, while offering an excellent tolerance profile, even on sensitive skin. Often described as a plant-derived alternative to retinol, bakuchiol does share some of its effects and mechanisms of action, notably its ability to stimulate collagen synthesis by dermal fibroblasts. This similarity is partly due to their respective chemical structures, which, while not identical, are closely related.

This frequent comparison with retinol can however cause confusion because the retinoids are known to be photosensitising and require increased caution during sun exposure.

Nevertheless, current studies indicate that the purified bakuchiol is not photosensitising. Photosensitisation risks are linked to crude extracts of Psoralea corylifolia, the plant source of bakuchiol, as these extracts can contain psoralens and furocoumarins, compounds known for their phototoxicity. These molecules increase skin sensitivity to sunlight by absorbing UVA rays, making them photoreactive. Once activated by light, they form covalent bonds with DNA and cellular proteins, generating reactive oxygen species that damage skin cells and cause redness and heat.

However, the bakuchiol used in cosmetics is obtained through a series of rigorous purification processes, including liquid–liquid extractions and chromatography steps that allow the removal of photosensitising compounds and the isolation of pure bakuchiol. Clinical studies on the bakuchiol confirm its tolerability: no photosensitisation reactions have been reported after use of a formulation containing this molecule.

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

However, although bakuchiol does not pose a risk of photosensitisation, we recommend you protect your skin with sunscreen each day. Sun protection is essential to prevent cellular damage that increases the risk of skin cancers, as well as the photoageing, regardless of the cosmetic ingredients 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).