From a skincare perspective, Hyaluronic acid and Sodium hyaluronate are often used interchangeably and more often than not, they are both regarded as Hyaluronic acid. However, these two molecules do have some subtle differences.
Sodium hyaluronate is the salt form of Hyaluronic acid that is less likely to oxidize, a more stable form of the two. It is also easier to formulate and cheaper to manufacture. Hence, Sodium hyaluronate is a common ingredient of choice for skincare companies to produce products that focus on hydration.
Another difference between the two molecules is the molecular size and weight. Hyaluronic acid has a much larger molecular size and higher molecular weight, therefore limiting it to work on smoothing and hydrating fine lines on the surface of the skin.
Sodium hyaluronate on the other hand has smaller molecular size and lower molecular weight, thus giving it the ability to penetrate deeper into your skin layers to hydrate your skin from inside out.