At what concentration is retinol effective in a cosmetic product?

Several scientific studies have demonstrated the effectiveness of retinol against signs of aging starting from 0.01%.

As a reminder, the retinol, also known as vitamin A, is a compound that belongs to the retinoid family. It is recognized for effectively acting on visible signs of skin aging such as wrinkles, pigmentation spots, or even loss of firmness and radiance. It stimulates cell renewal, tightens pores, and refines skin texture. Sensitive to light, this active ingredient is preferably used in the evening, for greater effectiveness.

Note : The European Cosmetic Regulation allows the use of retinol in leave-on products at a maximum concentration of 0.3%. Be aware, overdosing this active ingredient could at best be pointless, at worst dangerous. Indeed, at high concentrations, it can cause significant skin irritations.