Hyaluronic acid vs glycerin — which humectant is better?.

Hyaluronic acid and glycerin are the two humectants that appear most frequently in skincare formulations. They are both widely available, well-tolerated, and effective. The question of which is "better" is common and, in most contexts, less important than understanding what both do and how to use them.

What a humectant does

Humectants attract and hold water. In skincare, they are applied to the skin surface to draw moisture — either from the environment or from the deeper layers of the skin — and hold it at the surface. The result is a temporary increase in surface hydration, a plumped appearance, and improved skin texture.

Humectants are not film-forming occlusives (like petroleum jelly or silicones, which create a physical barrier to water loss), and they are not emollients (like squalane or shea butter, which soften and smooth). They draw water. That distinction matters for how they are used.

Glycerin

What it is. Glycerin (also called glycerol) is a simple polyol — a small, water-soluble molecule derived from plant or animal fats, or produced synthetically. It is one of the oldest and most studied skincare ingredients.

What the evidence shows. Glycerin is among the most effective humectants available. It is highly water-attracting, absorbs rapidly, and is exceptionally well-tolerated — sensitisation to glycerin is extremely rare. It has been the reference humectant against which other ingredients are compared in a significant proportion of hydration studies.

Concentration. Glycerin at 5–15% in a formulation produces meaningful surface hydration. At very high concentrations (above 30%), it can paradoxically cause a drying effect by drawing moisture from deeper skin layers in low-humidity conditions — a consideration in concentrated serums used in dry climates.

The formulation reality. Because glycerin is inexpensive, highly effective, and very stable, it appears in the vast majority of hydrating skincare products — including most products labelled with other humectants as the hero. When a product lists "hyaluronic acid" prominently, glycerin is often present in the formulation as well.

Hyaluronic acid

What it is. Hyaluronic acid is a polysaccharide — a type of carbohydrate — found naturally throughout the body, concentrated in synovial fluid and the skin's extracellular matrix. In skincare, it is typically produced via bacterial fermentation. It is available at different molecular weights, which affects its behaviour on and in the skin.

What the evidence shows. High-molecular-weight HA stays on the surface, forming a film that temporarily reduces water loss and leaves skin feeling smoother. Low-molecular-weight HA (LMW-HA) penetrates more deeply and has been studied for its interaction with dermal structures, including fibroblast activity. The surface effect — immediate hydration and smoothness — is well-documented. The deeper effects are more variable and formulation-dependent.

The marketing premium. Hyaluronic acid is marketed far more aggressively than glycerin, despite the evidence being broadly comparable for surface hydration. The "holds 1,000 times its weight in water" claim is technically accurate but misleading as a skincare metric — the practical effect on skin hydration is more modest and environmentally dependent. HA carries a significant price premium over glycerin, which does not correlate with a proportionate difference in hydration outcomes in most head-to-head studies.

Which is better?

For primary surface hydration, the evidence does not consistently show hyaluronic acid outperforming glycerin. Several well-controlled studies have found glycerin as effective or more effective as a humectant, at a fraction of the cost. The reverse is not reliably true either — both work.

Where HA has a meaningful advantage:

• LMW-HA has some evidence for fibroblast signalling and wound-response stimulation that glycerin lacks.
• HA's film-forming quality at high MW gives a distinctive surface feel — a plumped, smooth texture that some people prefer.
• For products designed to address deeper hydration concerns (not just surface moisture), a well-formulated multi-weight HA serum offers properties glycerin alone cannot.

Where glycerin has a meaningful advantage:

• More stable, more studied, cheaper, available at higher effective concentrations without formulation complexity.
• Better tolerated at high concentrations in most skin types.
• Less dependent on molecular weight considerations for basic humectant function.

In practice: a product with glycerin as its primary humectant is not inferior to one with HA — and is often more cost-effective for equivalent surface hydration.

The sealing step

Both hyaluronic acid and glycerin share the same limitation: in low-humidity conditions, both can draw moisture from the deeper layers of the skin rather than from the air, potentially increasing transepidermal water loss if used without a sealing layer. This is the consistently misunderstood aspect of humectant use.

Apply a moisturiser or occlusive over any humectant. The humectant draws water; the moisturiser seals it in. Used alone — in a dry climate, without a sealing step — a humectant serum can leave the skin drier than before. This applies equally to HA and glycerin.

The Lux & Glo moisturiser

The ritual formula uses squalane as its primary moisturising agent rather than a humectant. The reasoning is formulation-specific: squalane reinforces the lipid matrix directly, absorbs without needing a sealing step, and does not depend on ambient humidity. It is a different class of moisturising ingredient — an emollient — rather than a humectant.

This is not a position against HA or glycerin. Both are effective, well-tolerated ingredients with clear roles in hydration. Understanding what they do — and that glycerin does it comparably well for considerably less — is more useful than the marketing hierarchy would suggest.