Hyaluronic acid is the most widely used hydrating ingredient in skincare, and the most commonly misused – usually by people applying it to bone-dry skin and wondering why it made things worse. It's a simple ingredient once you understand what it's doing.
What it is
Hyaluronic acid occurs naturally in skin, where it holds water between cells and keeps tissue cushioned. In skincare it's used as a humectant: a substance that attracts and binds water, holding many times its own weight.
The "acid" in the name misleads people. It isn't an exfoliant, it has nothing in common with glycolic or salicylic acid, and it won't cause peeling or sensitivity.
What it's used for
Hyaluronic acid is chosen for the appearance of plumpness and the look of hydrated skin. Fine lines look softer when skin is well hydrated, which is why HA is so often associated with a smoother appearance — it's a hydration effect rather than a structural change, and it's immediate rather than cumulative.
Molecular weight
You'll see products advertising multiple molecular weights, and the distinction is genuine. High-molecular-weight HA is a larger molecule that stays on the surface, giving an immediate plumping look. Low-molecular-weight HA is smaller and settles into the upper layers for a longer-lasting hydration.
Formulas combining several weights aim to do both at once. It's a reasonable approach, though a well-made single-weight serum used correctly will serve most people perfectly well.
How to use it — the part that matters
Apply to slightly damp skin, then seal with a moisturiser. This is not optional advice.
Because hyaluronic acid draws water, it needs water available to draw. Applied to dry skin in a dry environment with nothing over the top, it can pull moisture from deeper in the skin and evaporate, leaving skin feeling tighter than before. That's the source of nearly every complaint about HA "not working" or "making my skin worse".
So: cleanse, don't dry your face completely, apply the serum, then moisturiser on top. In very dry conditions — aeroplanes, air conditioning, winter heating — be especially diligent about that final step.
What to pair it with
Anything. Hyaluronic acid is one of the few actives with no conflicts — it sits happily alongside retinol, the acids, vitamin C and niacinamide, and it's genuinely useful for making demanding routines more comfortable.
If your skin needs more than hydration alone, ceramides and squalane are the natural companions: humectants attract water, emollients and lipids help keep it there.
Explore our hyaluronic acid skincare, or see all active skincare.