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Pourquoi le pH des produits cosmétiques est-il important ?

Why is the pH of cosmetics important?

What is pH?

pH is the abbreviation for hydrogen potential. PH represents the amount of hydrogen ion (H +) present in a substance, the higher it is the more acidic the pH. The latter is measured on a scale of 1 to 14, the pH of 1 being the most acidic and the pH 14 the most basic. The skin's pH is generally around 5 (4.7 on average according to some studies *), that is to say it is acidic, as a benchmark the so-called neutral pH has a value of 7. acidity of the skin preserves the skin flora and the hydrolipidic film which protect it from harmful bacteria and external aggressions (abrasion, burns, friction, etc.). As a reminder, the skin flora and the hydrolipidic film form a barrier on the surface of the epidermis preventing the intrusion of pollutants and bacteria.

PH imbalance and skin problem

Whatever your origin or your skin type, its pH is acidic. Increasing its pH by applying basic cosmetics will decrease the integrity of the skin barrier and promote insensible water loss. A prolonged imbalance in the skin's pH leads to irritation, redness, pimples, dermatitis, but also acne or candidiasis. After the application of a basic cosmetic, the pH of the skin will be higher for several hours, promoting dehydration for dry skin or an overproduction of sebum for oily skin. In order to best protect the acid-base balance of your skin, you should favor cosmetics with neutral or acidic pH and moisturize the skin well. This is also true of hair covered with an acid mantle composed of a very fine fluid made up of sebum, sweat and water. The use of alkaline products weakens them, which gives the hair a dull and rough appearance with a tendency to break. Conversely, ingredients with an excessively acidic pH (<2.5) cause burns and lesions.

But how do you spot cosmetics that are too alkaline?

If you make your own cosmetics, systematically check the pH of your formulas before using them. For this, there is pH paper easy to find in pharmacies or on the internet.

Here are the active ingredients frequently found in cosmetic products and likely to unbalance the skin's pH:


Biosme a range of hygiene products with a protective pH

In developing the Biosme range, we have prioritized the preservation of the skin microbiome. This is why the pH of our formulas is very studied. DayDry and Biosme deodorants are slightly acidic and contain probiotic active ingredients, which strengthens the skin barrier and prevents the appearance of redness and / or pimples in the armpits. Biosme deodorant and shampoo wash gels also respect the skin's pH and strengthen the skin flora with their formula enriched with probiotic active ingredients.

* Before 2006, scientists located the pH of the skin between 5 and 6, depending on the areas of the body or gender. However, a study published in the International Journal of Cosmetic Science (H. Lambers et al., 2006, vol. 28) shows that the pH of the skin is, on average, at 4.7, ie at levels well more acidic than those usually found. To reach this conclusion, the researchers measured the pH of 330 people from Spain, the Philippines, the Netherlands and Germany, asking them not to wash for several days and not to use any cosmetics. The values usually observed are therefore the direct consequence of our hygiene practices. The pH of tap water (pH 7/8) and that of soaps (pH9 / 10) increase the pH level of the skin, weakening the skin flora which has the role of strengthening the first line of defense of the human body ( the acid mantle), preventing the invasion of harmful bacteria. Finally, this report shows that higher pH values, ie less acidic, are associated with increasingly widespread diseases such as atopic dermatitis, irritant contact dermatitis, acne or ichthyosis.

Source: International Journal of Cosmetic Science, 2006, 28, 359-370

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