How to properly use a cosmetic product?

Before purchasing a skincare product, particularly for those who are aware of their allergies, it is advisable to systematically analyse the list of ingredients to identify the potential presence of the allergen to which you are sensitised.

The predominant ingredients (those with a concentration greater than 1%) must be listed in descending order according to their quantity in the product. Below 1%, the so-called "minority" ingredients can be listed in no particular order.

Furthermore, the 26 most allergenic fragrance substances, regulated by Europe, must also be mandatorily disclosed to consumers on the ingredient list, if the concentration of any of these substances exceeds more than 0.001% in a leave-on product (cream, milk, lotion, etc.) or 0.01% in a rinse-off product (shampoo, shower gel, cleanser, mask, etc.).

Before the initial use of any cosmetic product, take the time to observe certain information, as mentioned on the product packaging or listed in the instructions, for safe usage:

• The frequency of use to avoid bringing about other issues due to excessive use such as redness, irritation, sensitivity, dryness, spots, etc.;

• The area where the product should be applied. Some skincare treatments are ideal for the body but can be harsh for the face;

• The application duration such as the time a mask or a depilatory is left on, for example, is crucial for the product to deliver its full effectiveness. However, leaving a product on for longer than recommended could have adverse effects on the skin or hair fibre, and thus produce the opposite effects than expected. Conversely, a product that is not left on for long enough may not have any effect at all;

• The necessity or not of rinsing after use, if the function of the product requires it (shampoo, exfoliant, shower gel, etc...) or if rinsing is clearly indicated (certain makeup removers, masks, etc.);

• The warnings such as "avoid the eye contour", "not recommended for sensitive and atopic skin", "use only in the evening", "avoid sun exposure during the period of use", etc. are there to prevent any discomfort.

Even when taking the usual precautions, the use of cosmetic products can trigger an allergic reaction in some individuals. It is therefore important to test each new cosmetic product on a small area of your body to see if the cosmetic ingredients contained in the product are suitable for you. Here is the procedure to follow:

1. Next, take a small amount of the product and apply it to the crease of your elbow, wrist, or behind the ear on clean, dry skin;

2. Leave the product on for 24 hours and observe the area: if no skin reaction occurs, then your skin tolerates the product. Conversely, if redness, irritation, tingling or itching occur, this indicates that you have had an allergic reaction to one or more components of the product.

Even though this test allows you to know your tolerance towards a new cosmetic product, it does not eliminate the possibility that prolonged use of the product may sensitise you.

Before applying any skincare product, remember to thoroughly wash your hands. This action helps to prevent the spread of germs and thus promotes the formation of skin impurities (blackheads, comedones, spots). Indeed, it is through the hands that dirt and bacteria are most easily transmitted. When they come into contact with the skin, bacteria penetrate the pores and cause the appearance of imperfections.

The fundamental principle is to start by applying products with a light, liquid, aqueous texture, and continue with products with an oily and thick texture, regardless of the number of products. Adhering to this order of application allows water to penetrate into the deep layers of the skin and, importantly, to be retained for optimal hydration.

This practice is counterproductive. By directly placing the serum pipette onto your skin, you expose your cosmetic product to greater risks of bacterial proliferation. Indeed, when bacteria come into contact with cosmetics, they can compromise their quality.

Some active ingredients contained in cosmetic products can cause skin sensitisation and trigger reactions such as burns, brown spots, redness, tingling... when exposed to sunlight after their application: this is referred to as photosensitisation.

essential oils

During the period of use of treatments containing photosensitising active ingredients, remember to protect your skin with the application of a broad-spectrum sunscreen that is suitable and limit as much as possible any exposure to UV rays.

Lipsticks, lip balms, lip oils, makeup powders, mascaras, lip pencils... certain categories of cosmetic products should not be shared, as this can significantly increase the risk of contracting and spreading microbes.

Some viruses, such as oral herpes, can be transmitted through contact with oral mucous membranes, leading to the formation of a cold sore. This is particularly the case when lip products are shared. Another example is the sharing of eye makeup (mascara, eyeshadow, etc.) which could result in conjunctivitis.

The brushes and other cosmetic accessories (sponges, brushes, etc.), which you use daily and are regularly in contact with your skin, also need to be cleaned from time to time with a suitable product. They are filled with makeup, dirt, dust, dead skin cells, bacteria...

Indeed, neglecting to clean them provides a veritable gateway for bacteria on your skin, in addition to contaminating your cosmetic products and compromising their quality. This could lead to acne, irritations, redness, an infection or even conjunctivitis. Therefore, it is recommended to clean your beauty accessories at least once a week, especially if they are used regularly.

Few are those who pay attention to the expiry date when purchasing a cosmetic product. On the contrary, many consumers find themselves using skincare products with a lifespan that has been significantly exceeded. However, there are two indicators that can be found on cosmetics that allow you to better track your cosmetic products:

• The minimum durability date (MDD), represented by a small hourglass or by the phrase "Best used before end/on...", corresponds to the deadline until which a cosmetic product can fulfil its functions and be used. Its mention is mandatory when the indicated MDD is less than 30 months. It consists of either the month and the year, or the day, the month and the year;

• The period after opening (PAO), represented by the symbol of an open jar, indicates the time frame during which the product can be used without any risk after it has been opened. It is mandatory when the minimum durability date (MDD) exceeds 30 months, which is often the case. The PAO is expressed in months (ex : 6M for 6 months).

Beyond this period of time, you risk the cosmetic becoming ineffective or experiencing side effects (redness, itching, inflammation, infection...).

It can be challenging to remember the opening date of your products. We advise you to make a habit of noting down the opening date after each initial use.

For optimal preservation, avoid exposing your products to temperature fluctuations, direct sunlight, humidity, and heat sources, and limit any contact with air. Additionally, most skincare products are water-based. Such an environment is particularly conducive to the proliferation of microorganisms (mould, bacteria, etc.).

When cosmetic products are exposed to such conditions, the organoleptic qualities (smell, texture, colour) can be altered, which would impair the quality of the product and lead to a faster degradation of the cosmetic formulas: the effectiveness of the product would then decrease.

To avoid such inconvenience, store your products in a dry, cool place, away from light. Also, ensure to properly close your containers after each use and remove any excess product.

If your cosmetic product exhibits a questionable appearance, meaning if the colour has darkened or lightened, the texture has changed (biphasic, granular, viscous, dry), if it contains a foreign body, if it emits an unpleasant odour of the rancid, acidic or alcoholic type or simply if it no longer has any scent, it has most likely "turned". This particularly concerns products that have already been opened and used. Indeed, as long as it has never been opened, a cosmetic product can be stored for a very long time without risk.

Conversely, if this is not the case, cease its use and do not hesitate to discard it. If you continue to use an expired product, you risk developing an allergy, a breakout of spots, redness or even worse, a skin infection. Moreover, the active ingredients contained in the skincare product no longer have any effect. Indeed, the product has been subject to numerous daily manipulations and thus to the development of real bacterial breeding grounds.

• AFSSAPS (Agence Française de Sécurité Sanitaire des Produits de Santé). Recommandations de bon usage des produits cosmétiques
  à l’attention des consommateurs (Novembre 2010).