Hyaluronic acid is the most reliably repeated ingredient name in skincare, which also means it carries the most reliably repeated exaggeration. Here's what it actually does, including a widely quoted number that a recent paper found doesn't hold up.
Hyaluronic acid (HA) is a sugar molecule your body already makes. It's found throughout skin, joints, and connective tissue, where its job is to hold onto water and keep tissue cushioned and pliable. Skin's own HA levels decline with age and sun exposure, which is part of why skin looks and feels less plump over time. Applied topically, HA works as a humectant: it draws water towards itself and helps skin hold onto moisture rather than losing it to the air.
The "1,000 times its weight in water" claim, checked
That figure appears on a great many hyaluronic acid products. A paper by Borchers and Pirrung went back to the experiments behind it and found no evidence that hyaluronic acid binds anywhere near 1,000 times its own weight in water. It's still an excellent humectant; the number simply doesn't hold up.
Why molecular weight actually matters
This is the part of hyaluronic acid that's usually skipped over, and it's the more useful fact for choosing a product. HA doesn't come in one size. Formulas use different molecular weights, and weight influences how it behaves:
- High molecular weight HA tends to sit on the skin's surface and form a film that can help reduce water loss, which gives a smoother, more hydrated feel.
- Lower molecular weights behave differently again. Different molecular weights affect film-forming and hydration properties, but penetration and clinical effects vary by formulation, and how far smaller fragments reach in a finished product is still debated. Research summarised by Papakonstantinou, Roth, and Karakiulakis in Dermato-Endocrinology describes size-dependent behaviour as central to how HA functions in skin, including its role in skin's water content as natural levels decline with age. That describes HA in skin generally, not the effect of a particular product.
Some formulas combine more than one molecular weight, with the aim of covering both surface film-forming and hydration properties. That describes the intent of the formulation rather than a proven difference in results.
Choosing between formats: what each is actually built for
Hyaluronic acid appears across much of our range. Here are six formulas where it plays a leading role, each built quite differently:
| Product | Formulated as | Best suited to |
|---|---|---|
| Weightless Hydration Gel | Hyaluronic acid plus watercress extract, in a water-based, oil-free gel | Oily or combination skin that wants hydration without shine or residue |
| Ceramide Cushioning Eye Cream | Hyaluronic acid plus shea butter and aloe juice | Eye-area hydration |
| Shea Marine Day Cream | Multi-molecular-weight hyaluronic acid plus a marine-derived ingredient | Daily hydration |
| Hexapeptide Smoothing Serum | Hyaluronic acid plus a signal peptide (Hexapeptide-11) | A hydrating serum used before moisturiser |
| Hyaluronic Acid Radiant Eye Cream | Multi-molecular-weight hyaluronic acid plus ginkgo biloba and horse chestnut extracts | Under-eye hydration |
| Ceramide Cocoon Night Cream | Sodium hyaluronate plus ceramide-family lipids | Overnight hydration and comfort |
The common thread across these six: hyaluronic acid is a supporting, hydrating layer in each of them, not the whole formula, and none of them replace a moisturiser on their own if you're using one as a standalone step. A humectant needs something to seal that water in, which is why a lighter hyaluronic-acid step still works best layered underneath a richer cream, not instead of one. In an evening routine, hyaluronic acid is commonly applied before an oil or serum. Our bakuchiol vs retinol guide covers what typically comes after in that kind of routine.
Topical hyaluronic acid isn't the same thing as an HA filler
Worth clearing up, because the same ingredient name gets used for two genuinely different things: injectable dermal fillers also use hyaluronic acid, but at a very different molecular weight and cross-linking, designed to sit under the skin and add physical volume for months at a time. A topical toner, serum, or cream cannot replicate that. It works on the surface and upper layers only, on hydration rather than structural volume, and its effects last as long as you keep applying it, not months from a single treatment. Neither is a substitute for the other; they're solving different problems with the same base ingredient.
A sensible way to use it
Apply to slightly damp skin rather than fully dry skin. A humectant needs some water nearby to draw from, and in very dry air it can occasionally pull moisture from deeper skin layers if there's nothing else available, which is part of why sealing with a moisturiser afterwards matters more than the marketing usually mentions. It's also climate-dependent: in a humid environment, HA can draw moisture from the air itself; in a very dry environment, giving it a damp base and sealing it in matters more, not less.
Sources
- Borchers S, Pirrung MC. “The Fallacy of Hyaluronic Acid Binding a Thousand Times Its Weight In Water.” ChemRxiv preprint, 2023.
- Papakonstantinou E, Roth M, Karakiulakis G. “Hyaluronic acid: A key molecule in skin aging.” Dermato-Endocrinology, 2012; 4(3): 253–258.
This article is educational and doesn't replace medical advice. If you have a diagnosed skin condition, check with your dermatologist before changing your routine.
The short version
What hyaluronic acid actually does for hydration, the water-binding claim that doesn't hold up under real testing, and how to tell which formula in a hyaluronic acid range actually suits your skin.
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