Can azelaic acid be used in the morning, before exposure to the sun?

Acne, lentigines, rosacea, melasma, photoaging... the azelaic acid has a variety of applications, which highlights its importance in various fields. In skincare, this ingredient, deemed effective, well-tolerated and relatively gentle, helps to regulate sebum production, reduce hyperpigmentation, calm inflammatory responses, combat bacteria responsible for blemishes, and neutralise free radicals that cause skin damage (brown spots, wrinkles, etc.).

Despite all these benefits, its reported slight exfoliating effect suggests that it might increase skin sensitivity to the sun, leading to the question of whether additional precautions should be taken before sun exposure when using an azelaic acid-based skincare product. However, azelaic acid is not known to increase skin sensitivity to UV exposure compared to normal, unlike some other common topical agents (AHA, benzoyl peroxide, etc.). Therefore, it is not implicated in the development of phototoxic reactions.

To date, no cases of photo-reaction have indeed been observed and reported when using topical medications (creams, gels, foams) containing azelaic acid, favourably distinguishing it from a number of other active ingredients. This means that azelaic acid does not appear to increase the risk of sunburn and it is possible to use it safely during the day. Similarly, it can be used regardless of sun activity, including in the summer.

Although azelaic acid is not a photosensitising active ingredient, it is always recommended to include a broad-spectrum sun care product with a high SPF in one's daily routine.