The hazards of retinol.

While the photosensitizing nature of retinol has not been clearly established, this molecule nonetheless remains unstable in light. Indeed, due to the numerous double bonds in its chemical structure, when retinol is exposed to UV rays, it is likely to undergo chemical degradation and transform into reactive intermediates. By oxidizing, retinol is responsible for the release of free radicals on the skin's surface. These reactive species can damage cell membranes, proteins, and DNA, promoting redness and burning sensations, symptoms similar to those of a sunburn. That's why it's recommended to use retinol treatments in the evening and apply sun protection the following morning.

This precaution applies to all retinoids (retinal, tretinoin, adapalene, etc.).

One of the most frequently reported transient side effects with the use of retinol is the skin purge, also known as the rebound effect. This phenomenon manifests as a pimple outbreak, similar to an acne flare-up, which occurs in the first few weeks of application. Although frustrating, the purge is actually a reflection of retinol's effectiveness. It follows a stimulation of cell renewal, which explains why active ingredients such as retinoids, AHAs, BHAs, or PHAs can trigger it. Indeed, by accelerating the skin regeneration process, these molecules allow the deep cells of the epidermis to rise to the surface more quickly, bringing with them imperfections that are still invisible. Without the purge, the skin would have expelled impurities more slowly, one by one over time.

The duration of the purge varies among individuals, but it generally resolves within 4 to 8 weeks. To limit the intensity of this reaction, we advise you to gradually introduce the retinol into your routine, starting with a low concentration and spacing out the applications.

Among the most serious dangers associated with the use of retinol is its teratogenic potential, that is, its ability to cause congenital malformations in the fetus. This risk is well-documented for oral retinoids, such as isotretinoin, but also applies, as a precautionary principle, to topical retinoids, like retinol or tretinoin.

Even though the skin's absorption of retinol is very low, this molecule can potentially enter the bloodstream. Retinoids are known to interfere with the signaling pathways of Vitamin A, which plays a crucial role in embryonic development, particularly in the central nervous system. Even minimal exposure, especially during the first trimester, poses a theoretical risk of causing severe abnormalities.

All retinoids, including those used in skincare, are strictly contraindicated for pregnant women, nursing mothers, or those planning to become pregnant.