8 misconceptions about retinol.

Yes and no.

Retinol is an active ingredient with a sensitizing power, which can cause skin dryness, tingling, tightness, discomfort, flaking, redness... That's why it is generally not recommended for sensitive and reactive skin. Irritation after applying a skincare product should not be interpreted as a sign of effectiveness. On the contrary, it indicates that the product is not suited to the skin's needs and is not appropriate for it.

With that being said, it's important to note that the retinol requires a period of skin adaptation ; if slight, tolerable redness appears, it doesn't necessarily mean you need to stop using it, but rather space out the applications to every other night, or even every third night. Additionally, it's also possible to start with a low dose, such as 0.01% or 0.05%, and then gradually increase the concentration of retinol. As a reminder, the use of this active ingredient in non-rinse cosmetic products is limited to 0.3% by European Regulation No 1223/2009.

As with any skincare product, before incorporating a new retinol-based product into your routine, we advise you to perform a skin patch test to ensure your skin tolerates it well.

No.

It's true that retinol is primarily known for its skin benefits. However, this active ingredient is also found in certain shampoos or hair serums where it mainly helps to prevent the buildup of dead cells on the scalp's surface. Indeed, although retinol is not considered an exfoliant per se, it accelerates cell renewal and aids in normalizing desquamation, which contributes to the rapid removal of epidermal cells. This hair property of the retinol is particularly beneficial for individuals prone to dandruff, as it is the result of clusters of epidermal cells sticking together.

Furthermore, some studies suggest that retinol could promote hair growth, in combination with minoxidil, a medication sometimes prescribed for androgenetic alopecia. Research in vitro on human hair follicles focused on this combination in 2007. For this, researchers incubated human hair follicles with different concentrations of minoxidil, with or without retinol, for 12 days. Hair growth was then monitored. Significantly greater growth was observed in the hair follicles incubated with 1 µM of minoxidil and 17 nM compared to those in the culture medium with only 1 µM of minoxidil, as shown in the graph below. Thus, it is possible that retinol may enhance the action of minoxidil on hair, although more investigations are still needed. Furthermore, only the combination of minoxidil and retinol has been studied. It is not certain that retinol alone has the same action.

No.

Although it may not be visibly apparent, cellular degeneration begins around the age of twenty. This is the ideal time to start incorporating active ingredients that can help prevent skin aging. Indeed, from the twenties, the production of collagen and elastin, the dermal proteins that underpin the skin and ensure its flexibility and elasticity, begins to decrease. In addition, glycosaminoglycans, such as the hyaluronic acid, also see their synthesis reduced, making the skin more prone to dehydration, volume loss, and the appearance of wrinkles and fine lines.

It is entirely possible and relevant to incorporate retinoids into one's skincare routine starting in their twenties.

Yes.

In 2018, the European Medicines Agency (EMA) decided to standardize the contraindications related to pregnancy for medications containing a retinoid, whether they are administered orally or topically.

Before this update, only oral forms of retinoids, such as isotretinoin, better known by the drug name Roaccutane, were formally contraindicated due to their proven teratogenic effects that can lead to severe congenital malformations. However, following a reevaluation of the benefit/risk ratio regarding retinoids as a whole, the EMA has extended this contraindication to topical retinoids. Indeed, these molecules play a role in embryogenesis and reproduction.

From a mechanistic perspective, the teratogenic effects of retinoids are caused by changes in cell migration and differentiation. More specifically, isotretinoin disrupts the movement of neural crest cells, a cell population crucial for the development of the nervous system, which can lead to their cell death. This disruption explains the occurrence of malformations in craniofacial, cardiac, and thymic structures characteristic of retinoids. Additionally, retinoids affect brain development, particularly in the rhombomere region, involved in the formation of certain parts of the central nervous system. This can result in severe abnormalities, such as cerebellar hypoplasia, meaning insufficient development of the cerebellum, or a malformation of the spinal cord. These effects can harm brain functions and affect intellectual and motor development. Although no study has been specifically conducted on retinol, the same precautionary principle applies to this derivative of vitamin A: this active ingredient should not be used during pregnancy.

Note : The same applies during breastfeeding. Retinoids should not be used during this period as there is a significant risk of transmission to the child.

Yes.

It is often said that retinol and retinoids in general are photosensitizing. However, scientific studies regarding the photosensitizing potential of topical retinoids do not support this claim and fail to show that the application of retinoids makes the skin more sensitive to the sun. It's important to note that we're only discussing topical retinoids here, as isotretinoin is considered photosensitizing by the Food and Drug Administration (FDA), the American agency responsible for monitoring food and drug products. Nevertheless, despite the lack of evidence concerning the risks of photosensitization induced by retinol and topical retinoids, it is true that it is better to use these active ingredients in the evening.

Indeed, like all retinoids, retinol is a molecule that contains numerous conjugated double bonds in its chemical structure. This characteristic makes these compounds susceptible to undergoing photochemical reactions, such as isomerization, dimerization, or even oxidation. Therefore, when exposed to sunlight, the retinol present on the skin's surface can transform into various reactive intermediates that can be harmful to the skin. That's why it's recommended to apply retinol and retinoids in general at the end of the day and to use sun protection the following morning.

No.

The concern that retinol may promote cancer primarily rests on its mechanism of action: by stimulating cell renewal, it could theoretically accelerate the proliferation of already abnormal cells. However, to date, no scientific study has validated this hypothesis.

Contrarily, some retinoids are sometimes prescribed for their beneficial effects in managing certain cancers. For instance, synthetic retinoids like tazarotene or bexarotene are used in the treatment of precancerous lesions such as actinic keratoses, or even in some rare forms of cutaneous lymphomas. These molecules belong to the same family as retinol and work by modulating the expression of genes involved in proliferation, differentiation, and cellular apoptosis. Isotretinoin, on the other hand, can be used in support of immunotherapy to treat high-risk or recurrent neuroblastoma. These treatments are administered after high-dose chemotherapy and rescue by stem cell transplant.

Yes and no.

It's true that retinol is generally not recommended for sensitive and reactive skin. However, this doesn't mean that these skin types should exclude all retinoids from their skincare routine. Indeed, not all retinoids are equal in terms of potency and tolerance. Retinol esters, requiring more conversion steps than retinol, are gentler and can be used by sensitive skin. Some so-called next-generation retinoids, like the hydroxypinacolone retinoate, are also known to be better tolerated by sensitive skin.

Finally, encapsulated retinoids pose a lower risk of irritating the skin as encapsulation systems allow for a gradual and controlled release. The distribution of the active ingredient in the skin becomes more uniform and its accumulation in the stratum corneum is limited, as is the rapid activation of retinoic acid receptors. The encapsulation of retinoids can be done in liposomes or in polymeric nanocapsules.

No.

Contrary to a persistent rumor, retinol is not about to be banned in Europe. This confusion stems from recent evaluations conducted by the Scientific Committee on Consumer Safety (SCCS), which examined the safety of retinoids in cosmetic products. The aim of these studies is not to ban these molecules, but to better regulate their use to ensure consumer safety. In November 2023, the SCCS recommended limiting the concentration of retinol in cosmetic products to 0.05% for body products and 0.3% for facial care products.

Therefore, this is not a prohibition of retinol, but a regulatory adjustment.

• LOTAN R. & al. Retinoids and their receptors in cancer development and chemoprevention. Critical Reviews in Oncology/Hematology (2002).

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

• Règlement (CE) No 1223/2009 du Parlement Européen et du Conseil.

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

• GUDAS L. J. & al. Retinoids, Retinoic Acid Receptors, and Cancer. Annual Review of Pathology: Mechanisms of Disease (2011).

• PLUTZKY J. & al. Retinoid metabolism and diabetes mellitus. Diabetes and Metabolism Journal (2012).

• QUAN. T. & al. Molecular basis of retinol anti-aging properties in naturally aged human skin in vivo. International Journal of Cosmetic Science (2016).

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