To be effective, they must be part of an overall approach to healthy hygiene and adapted to the needs of the skin (which vary with age, the seasons, etc.). Price is not an indicator of quality or results. It remains preferable to always opt for products that contain little or no controversial ingredients. And be aware of the fact that there are no miracle beauty products.
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Cosmetics Are Not Miracle Products!
Summary
- What Is a Cosmetic Product?
- How Far Do Cosmetics Penetrate the Skin?
- How Long Does a Cosmetic Product Take To Work?
Published February 29, 2024,
by
Maylis, Chemical Engineer
—
5 min read
What Is a Cosmetic Product?
Here is the definition of a cosmetic by the ANSM (French Agency for the Safety of Medicines and Health Products).
“A cosmetic product is defined as any substance or mixture intended to be placed in contact with the superficial parts of the human body (epidermis, hair and capillary systems, nails, lips and external genitalia) or with the teeth and oral mucosa with a view, exclusively or mainly, to cleaning them, perfuming them, modifying their appearance, protecting them, maintaining them in good condition or correcting body odors.
Cosmetic products placed on the market must be safe for human health. They are not subject to pre-market authorization. It is therefore up to the responsible person associated with each cosmetic product to guarantee that their products meet the requirements of the cosmetic and legislative regulations and regulatory guidelines, as well as to ensure that they present no risk to health.”
In other words, neither are there any cosmetic miracle products nor is skincare a medicine! It has no therapeutic action whatsoever and does not treat skin disorders. Unlike medicines, they do not require marketing authorization (MA) before they can be marketed. The evaluation of their efficacy and tolerance is also different from that of drugs. Nevertheless, they can still have a visible effect on the skin, provided their use is accompanied by a healthy lifestyle and a beauty routine consistent with the skin's needs.
How Far Do Cosmetics Penetrate the Skin?
The ingredients in a cosmetic product generally penetrate the stratum corneum, the most superficial layer of the skin, to diffuse into the deeper layers. However, there must be limits: the active ingredients in cosmetic products must never enter the bloodstream. Their action must remain superficial and local.
When a cosmetic product is applied to the skin, it must first pass through the stratum corneum, made up solely of dead cells called corneocytes. If it contains small active ingredients such as caffeine (molar mass = 194.2 g/mol) and hydrophilic compounds, it takes the so-called trans-cellular route (passage of active ingredients from cell to cell). In the case of lipophilic skincare products (made up of fatty substances), the intercellular route is preferred: active ingredients circulate in the inter-lipid cement that ensures the cellular cohesion of the horny layer, then in the interstitial liquid that fills the spaces between the cells in the deeper layers of the skin.
Generally speaking, in cosmetics, molecules act on the epidermis but do not reach the dermis, or only in minimal quantities. For an active ingredient to reach the dermis, several intrinsic and extrinsic conditions must be met:
The molecule must be tiny, like caffeine or low-molecular-weight hyaluronic acid;
Skin hydration must be optimal, and the skin must be neither too oily nor too dry;
Small amphiphilic molecules that are attracted to both lipids and water are those that penetrate deepest;
The thickness of the layer of product applied to the skin and the frequency of application have an influence on the penetration of active ingredients.
How Long Does a Cosmetic Product Take To Work?
In general, it takes a maximum of four weeks to see the effects of a cosmetic treatment on the skin. This corresponds roughly to the time it takes for cells to renew themselves (known as the cell cycle). Nevertheless, some active ingredients can have an effect on the skin's appearance and disorders in just a few days. This is the case, for example, with salicylic acid, which acts on imperfections in three days when concentrated at a minimum of 2%, even though skincare containing this active are no miracle products. As for lightening/anti-spot cosmetics, it's best to wait around six weeks before noticing the effects (or otherwise) on the skin. Hyperpigmentation is a complex phenomenon involving a large number of cells and biological mechanisms.
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