How to use retinol?

Recommended for mature skin as well as young and oily skin, with or without blemishes, retinol is an active ingredient that could almost be described as a cosmetic multi-tool. Indeed, it has numerous benefits for the skin, particularly due to its ability to accelerate cell renewal. By doing so, it helps to eliminate blemishes and melanin-loaded cells more quickly, a useful property in cases of hyperpigmentation, but also to achieve a smoother complexion. Furthermore, its antioxidant virtues help to prevent the appearance of ageing signs by neutralising free radicals.

The retinol also has a use in hair care, although it is less common. By promoting cell renewal, it accelerates the removal of cells from the horny layer, which can be relevant for individuals prone to dandruff. However, despite its effectiveness, the retinol is a recognised irritant and drying agent. Find below some advice for using it optimally and avoiding any skin discomfort:

• Incorporate retinol gradually into your skincare routine :

  If you wish to commence a skincare routine based on retinol, start by using a product containing a low percentage of this active ingredient, around 0.01-0.05%. Initially, opt for a spaced application frequency, applying every third evening for two weeks, then every other evening, and eventually every evening if your skin tolerates it. This method of use allows your skin time to adapt to this new molecule. You can then switch to a different retinol product and increase its concentration to 0.2, or even 0.3% (the maximum concentration permitted by European cosmetic regulations in a non-rinse product).

• Use retinol in the evening and apply a broad-spectrum sun protection the following morning :

  Retinol is a photosensitive molecule, meaning it is prone to degrade into reactive intermediates. When oxidised, 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 sunburn. For this reason, it is advisable to apply retinol-based treatments in the evening, before going to bed. The following morning, do not forget to protect your skin with a broad-spectrum sun cream.

• Combine retinol with a moisturising treatment :

  Retinol can be drying, particularly for the most sensitive skin types, so pairing it with a hydrating ingredient, such as hyaluronic acid, during your skincare routine can be beneficial. It's also possible to use the so-called "retinol sandwich" method, which involves applying the retinol treatment between two layers of moisturising cream. This helps to reduce the risk of irritation while gradually acclimatising the skin to the active ingredient.

Note : In all instances, before using a retinol-based treatment, as with any new skincare product, we advise you to conduct a skin tolerance test. To do this, apply a few drops to the inside of your arm and wait approximately 48 hours. If you observe a reaction, do not use this product on your face and rinse immediately. It's worth noting that today, skincare brands implement several strategies to reduce the risk of irritation caused by retinol.

Oral retinoids are derivatives of vitamin A prescribed for certain dermatological diseases, particularly severe or resistant forms of acne. The most well-known among them is isotretinoin. Unlike topically applied retinoids, oral retinoids act systemically, that is, they affect the entire body. Their mechanism of action is based on several combined effects, including a drastic reduction in sebum production through atrophy and decreased activity of the sebaceous glands, a direct keratolytic effect, an anti-inflammatory action, and an antibacterial effect.

The use of oral retinoids requires close medical supervision as their effectiveness is accompanied by significant side effects.

The most concerning aspect is their teratogenic effect, meaning the ability to cause foetal malformations during pregnancy. Therefore, effective contraception is imperative during treatment and up to a month after its cessation. Regular blood tests are also required to monitor liver function and blood lipid levels, which can increase under treatment.

The dosing regimen for oral retinoids is individualised and depends on each person's weight and tolerance. For example, isotretinoin is prescribed at doses ranging from 0.5 to 1 mg/kg/day, with a cumulative target around 120 to 150 mg/kg, achievable after several months of treatment. To limit the purge and side effects associated with isotretinoin, it is possible to start with a low dosage (0.2 mg/kg/day) and gradually increase it. Reaching the cumulative dose maximises the chances of long-term remission.

• KAFI & al. Improvement of naturally aged skin with vitamin A (retinol). Archives of Dermatology (2007).

• KIM K. H. & al. The Additive Effects of Minoxidil and Retinol on Human Hair Growth in Vitro. Biological and Pharmaceutical Bulletin (2007).

• QUAN T. & al. Molecular basis of retinol anti-ageing properties in naturally aged human skin in vivo. International Journal of Cosmetic Science (2017).

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