When and how frequently should retinol be used?

Retinol is part of the retinoid family and is one of the most well-documented active ingredients in dermatology. Once applied to the skin, it is gradually converted into retinoic acid, its biologically active form. This metabolite binds to nuclear receptors known as RARs (Retinoic Acid Receptors) present in keratinocytes and fibroblasts. This connection triggers a cascade of genetic transcription that leads to increased cell renewal, stimulation of type I and III collagen synthesis, reduction in the activity of metalloproteinases, enzymes that degrade the dermis' support fibres, and regulation of melanin production. These various mechanisms of action make retinol a valuable ally for smoothing fine lines, improving skin texture, and reducing pigmentation spots.

However, despite its benefits, retinol can cause irritation reactions in some individuals, particularly at the beginning of its use. Among the most frequently associated side effects of retinol are the emergence of redness, skin peeling, and sensations of tightness or burning. This can be explained as follows: by activating cellular renewal, retinol temporarily disrupts the skin barrier, leading to an increase in water loss and thus skin sensitivity.

The skin requires an adaptation phase during the initial uses of retinol or retinoids. The strategy is based on two pillars: the frequency of use and the chosen concentration.

To avoid weakening the skin and allowing it to acclimatise to retinol, it is advised to start with a low concentration, between 0.01-0.05%. This will also allow you to check that your skin tolerates this active ingredient well. We also recommend that you start by using it once every three evenings for two weeks. If you do not observe any reaction on your skin, you can gradually increase the frequency, first to every other evening, then to an application every evening if your skin can tolerate it.

The retinoids are active ingredients that should be used exclusively in the evening. This is because, when exposed to sunlight, they can break down and produce compounds that are harsh on the skin. Furthermore, it is important to use a sunscreen the following day.

It's important to note that, during the initial weeks, it's essential to not combine retinol with other potentially irritating active ingredients, such as AHA, BHA or pure vitamin C. Once your skin has become accustomed to retinol, you can reintroduce these active ingredients into your skincare routine, preferably by alternating the days of application. The so-called "retinol sandwich" method is also useful in the beginning: it involves applying a layer of moisturising cream before the retinol, and another one after, to create a barrier that limits the rapid penetration of retinol into the epidermis. This technique is particularly recommended for sensitive skin.

Note : If your skin does not tolerate retinol, you can consider retinoid esters, such as the hydroxypinacolone retinoate, a mild form of retinoids. Highly effective as it can act on RAR receptors without conversion, the hydroxypinacolone retinoate is also better tolerated due to its ester function which slightly slows its skin penetration, thus contributing to a gradual release.

There isn't a specific age to start using a retinoid as it entirely depends on the skin's needs. However, we can distinguish two approaches: dermatological use, for imperfections, and cosmetic use, for signs of ageing. From adolescence, retinoids, such as tretinoin or adapalene, can be prescribed to treat acne and normalise keratinisation. In this case, the use of retinoids is strictly supervised by a dermatologist.

To prevent or correct the early signs of ageing, one can consider using cosmetic retinoids, which are available without a prescription, from the twenties onwards. This period is indeed a turning point for the skin as its collagen production begins to slow down. It may then be relevant to incorporate retinol into one's skincare routine, to stimulate the activity of fibroblasts and support collagen synthesis. This can help to smooth emerging fine lines and improve skin texture. That said, there is no universal time to start using a retinoid: each skin has its own pace and it's never too late to reap the benefits. A double-blind study involving 23 people with an average age of 87 indeed showed that daily application of a 0.4% retinol lotion significantly reduced wrinkles after eight weeks.

It's not so much the age that determines the right time to start using a retinoid, but rather the skin's needs and its ability to tolerate it.

• SCHUMACHER W. E. & al. Improvement of Naturally Aged Skin With Vitamin A (Retinol). Archives of Dermatology (2007).

• LIN C. B. & al. A novel anti-ageing mechanism for retinol: induction of dermal elastin synthesis and elastin fibre formation. International Journal of Cosmetic Science (2011).

• ZASADA M. & al. Retinoids: active molecules influencing skin structure formation in cosmetic and dermatological treatments. Advances in Dermatology and Allergology (2019).

• ERKIERT-POLGUJ A. & al. A Clinical Anti-Ageing Comparative Study of 0.3 and 0.5% Retinol Serums: A Clinically Controlled Trial. Skin Pharmacology and Physiology (2020).