Cosmetics increasingly boast about having ‘isotonic’ formulas. This complex term is often misunderstood by the general public: it refers to a cosmetic product which preserves the nature of the skin.
An isotonic formula defines the balance between two different environments.
For example, when two liquid environments are placed in contact with each other, isotonicity consists in making their concentrations in molecules (minerals, trace elements, sugars, proteins…) equivalent.
When you talk about the isotonicity of a cosmetic product, it indicates the formula is designed to act in osmosis with the skin.
In practical terms, when a solution or any cosmetic product is isotonic for the skin, it means its content in mineral salts and trace elements is comparable to that of the tissues. This equivalent concentration helps preserve the integrity of these cells. The balance between the intracellular and extracellular compartments is maintained.
In theory, these cosmetics, in total affinity with the skin, prevent any skin reaction.