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Humectant · Hyaluronic Acid

Hyaluronic acid: the evidence is one 20-person trial, and we could not verify that it pulls water out in dry air

Holding many times its weight in water is a beaker result. The human trial we found compared it with a ceramide cream in 20 people with atopic dermatitis, and the two products did not differ.

Last checked Sep 16, 2026

In pregnancy
Not established
Irritation
Minimal
Daytime use
✓ Fine

Not a measurement — reported irritation grouped into five steps. It varies between people.

Korean classification Being checkedThe regulatory class has not yet been confirmed against a primary document. It will be filled in once it is.

Hyaluronic acid holds water. Numbers like 'a thousand times its own weight' follow it around, but that is measured in a beaker, not on skin.

It barely irritates and goes into almost everything, which suggests a thick evidence base. Go looking for human trials and there are fewer than you would expect.

Contents
  1. In 20 people with atopic dermatitis it did not differ from a ceramide cream
  2. We could not find the basis for 'in dry air it pulls water out of the skin'

What is established

The same ingredient at a different strength, in a different formula, is a different product. These are the conditions the studies used.

Moderate evidenceConcentration studied — Not established

In 20 people with atopic dermatitis it did not differ from a ceramide cream

A double-blind split-body study in 20 people with mild-to-moderate symmetrical atopic dermatitis covering at least 10% of body surface. Using the arms or legs as the target site, one side received a hyaluronic-acid-based emollient foam and the other a ceramide-containing emulsion cream.

Erythema, scaling and lichenification were rated by subjects and investigators.

What this design can show is the difference between two products, nothing more. With no untreated side, it cannot say what hyaluronic acid does as a moisturiser in the first place. And there were 20 participants.

Still, it is a result on human skin, so: moderate. That is a different tier of evidence from holding water in a beaker.

  • Randomised controlled trial in people · 20 participants · Compared with another active ingredient · Funding not declared · Endpoint scores from blinded assessors PMID 21896129
Not establishedConcentration studied — Not established

We could not find the basis for 'in dry air it pulls water out of the skin'

The explanation is everywhere: at low humidity, hyaluronic acid draws water up from the dermis instead of from the air, leaving skin drier. Given how humectants behave physically, it is a plausible story.

But we found no trial demonstrating this on human skin (PubMed, checked 16 September 2026).

Not established does not mean wrong. It means this site does not treat plausibility as evidence. If something turns up, this entry and its level will change.

Until then there is one practical takeaway: applying something occlusive over a hyaluronic acid product costs nothing whichever account is right.

How to use it

  • Apply to damp skin and seal it in. It holds water, so there has to be water to hold.
  • Products use different molecular weights, but molecular weight does not appear on an ingredient list. There is no way to check the difference from the label.
  • It barely irritates, so it layers easily with other ingredients.

Cautions

  • Topical hyaluronic acid and injectable fillers are completely different things. This page covers only the topical kind.
  • Figures like 'a thousand times' are beaker values. They do not mean that much water is held in skin.
  • We found no established data on use during pregnancy.

With a new ingredient, apply a small amount somewhere inconspicuous, such as the inner arm, for two days first. Stop if it reddens or stings.

Related skin concerns

Dryness

What this article relies on

  1. PubMed — 미국 국립의학도서관 문헌 데이터베이스National Library of Medicine · Checked on 2026-09-16