Ingredient Library
Hyaluronic Acid
Sodium Hyaluronate
The humectant that holds a thousand times its weight in water.
Hyaluronic acid shows up in almost every “+hydrating+” serum on the shelf, but the label rarely tells you the detail that matters most: molecular weight. Different sizes of HA behave differently in skin — and that, more than a big percentage claim, determines how hydrating your formula actually is.
INCI
Sodium Hyaluronate
Solubility
Water soluble
pH Range
5.0–8.0
Effective Range
0.1–2%
01 — What Is It
A Polysaccharide Native to Your Skin
Hyaluronic acid is a glycosaminoglycan — a long-chain polysaccharide — naturally present in your dermis, synovial fluid, and connective tissue. It sits in the extracellular matrix, binding and organizing water around skin cells so they stay cushioned and flexible. With age, stress, and UV exposure, its production and quality decline, which is one reason skin looks thinner, drier, and less bouncy over time.
Molecular weight is what changes how HA behaves: high molecular weight HA stays closer to the surface, forming a flexible film that visibly plumps and smooths. Low molecular weight HA can move a bit deeper and interacts more with cells, influencing signalling and collagen production. Sodium hyaluronate, the sodium salt of HA, is smaller and more stable, which is why it’s the form you usually see on ingredient lists.
Why It Matters
Sodium hyaluronate is the salt form of hyaluronic acid — smaller, more stable, and easier to formulate with. It’s what you’ll see in almost every well-made hydration serum.
02 — Mechanism
How It Works in Skin
Hyaluronic acid doesn’t “fix” your barrier on its own. It changes how water moves through the outer layers of skin — which can either support or stress your barrier depending on the formula and how you use it.
ONE
Humectancy
As a humectant, HA draws water from the dermis and, when available, from the surrounding environment into the stratum corneum. A single HA chain can bind up to 1,000 times its weight in water. If you apply it to dry skin in very dry air, it can end up pulling from your own skin instead of the atmosphere, leaving things tighter rather than dewy.
TWO
Barrier support
High molecular weight HA forms a soft, flexible film on the surface of skin that slows down transepidermal water loss (TEWL). You get an occlusive-like benefit — less water escaping — without using true occlusives or heavy oils, which helps support barrier function in lighter textures.
THREE
Wound healing & signalling
Low molecular weight HA fragments can act as “danger” signals (DAMPs), nudging cells to ramp up collagen production and migrate to repair sites. Higher molecular weight HA, in contrast, tends to be calming and anti-inflammatory. Together, these signalling roles are part of why HA shows up in wound-healing and post-procedure formulas.
Why It Matters
Not all hyaluronic acid is the same — a serum listing “hyaluronic acid” without specifying molecular weight is giving you half the picture.
03 — Concentrations
A Little Goes a Long Way
Hyaluronic acid is effective at very low percentages. Pushing the number higher doesn’t automatically mean more hydration — it mostly means a thicker, gummier texture. The vehicle, molecular weight profile, and how HA is layered in the formula matter far more than a “2% HA” claim on the label.
0.1–0.5%
Effective hydration range; most clinical studies use this window.
1–2%
High viscosity, gel-like textures; at this range HA often functions as the gelling agent itself.
0.5–1%
Noticeable plumping, good film-forming, and works in most formulas without becoming too thick.
Above 2%
Very high viscosity and difficult to formulate; rarely adds meaningful hydration benefits beyond texture.