Hyaluronic acidHA · Sodium hyaluronate
A humectant that holds water at the skin's surface — hydration, not rejuvenation.
Hyaluronic acid is a sugar molecule that occurs naturally in skin and binds a large amount of water. In skincare it is used as a humectant: an ingredient that draws and holds moisture in the outer layers.
It matters because trials of topical hyaluronic acid do show measurable short-term improvements in skin hydration and the look of fine, dryness-related lines. But its molecule is large, which limits how far it penetrates, so a serum is not delivering the same thing as an injectable filler despite the shared name.
In practice, hyaluronic acid is a good moisturising ingredient — best applied to damp skin and sealed with a moisturiser — rather than a treatment that changes skin structure; the structural evidence sits with sunscreen and retinoids.
Sources
Related terms
Written and reviewed by Mathew Beale, MSc Biotechnology, University of Reading.
Last reviewed: