Does Hyaluronic Acid Actually Do Anything?

Hyaluronic acid is a sugar your skin already makes. Its job in the body is to hold water, and it is remarkably good at it. Applied to the surface of the skin it does a modest, real, well-documented thing: it draws water into the outer layers and holds it there for a while, which makes skin look smoother and feel softer.

That is the whole claim, and it is true. Most of the confusion comes from expecting more than that, or from reading the label the wrong way.

The most common active there is

Why it sits low on the list, and why that is fine

In how to read an ingredients list we gave a rule: an active that appears after the preservatives is present in a small amount. Hyaluronic acid is the exception that proves the rule, and it is worth understanding why.

It works at very low concentrations. Somewhere between 0.1% and 2% is typical, and above about 2% the product turns into a gel too thick to spread. So a formula with a working amount of hyaluronic acid will almost always list it below the 1% line, because that is where a working amount lives.

What the label will not settle

The one thing that does change how it behaves is the size of the molecule, and the list cannot tell you that reliably.

• High molecular weight stays on the surface and forms a film that holds water there. This is the classic, immediate, smoothing effect.
• Low molecular weight is broken into smaller pieces that sit a little deeper in the outer layers. On a label this usually appears as hydrolyzed hyaluronic acid, and sometimes as sodium acetylated hyaluronate, a modified form.

A product that lists both plain sodium hyaluronate and hydrolyzed hyaluronic acid is genuinely using more than one size. Beyond that, claims like “five molecular weights” cannot be checked from the list, and there is no strong evidence that more sizes means a better product.

The dry-air worry

You may have read that hyaluronic acid pulls water out of the deeper skin in a dry room and leaves you worse off. The evidence for that is weaker than the warning suggests, and it is not a reason to avoid the ingredient. It is a reason to use it the way it works best anyway:

1. Apply to damp skinGive it water to hold. Straight after cleansing, or after a toner, before the face has dried.
2. Seal itFollow with a moisturizer. Hyaluronic acid holds water; it does not stop water leaving. The moisturizer does that part.

What it will not do

• Replace a moisturizer. It is a humectant, not an occlusive. On its own in a dry room it is a serum with nothing on top.
• Fill lines. The plumping you see is hydration and it lasts as long as the hydration does. Injected hyaluronic acid is a different product doing a different thing.
• Need a dedicated serum. Given how many products already contain it, buying a separate hyaluronic acid serum is optional. Useful if your routine has no hydrating layer; redundant if it has two.

Related reading

Since it turns up in nearly half of all toners, the toner question is really the same question: see do you need a toner. And for where a hydrating serum goes in the sequence, what order to apply skincare in.