What concentration of hyaluronic acid is most effective for the skin?

Hyaluronic acid is a glycosaminoglycan found in the extracellular matrix of the dermis, playing a significant role in its metabolism. Being highly hydrophilic, this macromolecule can retain up to 1000 times its weight in water, making it a key agent in maintaining the skin tissue's hydration. Due to its moisturising properties, hyaluronic acid is widely used in cosmetics. Its concentration in skincare and haircare products is not strictly regulated, however, it is generally incorporated at rates between 0.01 and 3%. In addition to its effects on the skin, hyaluronic acid has thickening properties for products, making it difficult to formulate beyond 1% and likely to cause pilling.

Regarding the effectiveness of skincare products containing hyaluronic acid, it is not necessarily correlated with the concentration of the active ingredient. Indeed, an independent study conducted in 2011 with 76 volunteers showed that the twice-daily application of a cream with 0.1% hyaluronic acid salts hyaluronic acid could significantly increase skin hydration (≈ +10%) and elasticity (≈ +20%), and reduce wrinkle depth (≈ -10%).

Furthermore, we have compared two non-independent clinical studies, each focusing on the effects of a serum with 0.4% hyaluronic acid and a serum with 3% hyaluronic acid respectively. The first study involved 52 volunteers who applied the product daily for four weeks. The second study relied on 22 individuals who used the skincare product twice a day for four weeks. The results obtained regarding skin softness and firmness are compiled in the table below. It should be noted that this assessment should be taken with caution as it is based on purely qualitative observations, made by the volunteers themselves, and not on quantified results. Moreover, this is by no means a comparative study between the two serums, as the participants differed from one study to another.