Hyaluronic acid: cross-linked vs. non-cross-linked – simply explained

In short: Not all hyaluronic acid is the same. Cross-linked hyaluronic acid is stable and holds its shape — used in classic fillers for volume and contours. Non-cross-linked hyaluronic acid is more fluid, breaks down faster, and boosts moisture and skin texture — used in skin boosters. Molecular weight also matters because it determines how deeply the molecule acts.

When you hear "hyaluronic acid," you might think of lip fillers or moisturiser. Both are hyaluronic acid – and yet they are completely different things. The reason lies in two properties: cross-linking and molecular weight. We explain both from scratch.

What does "connected" actually mean

Hyaluronic acid consists of long chains. In its natural form, the body breaks down these chains within one to two days. This is too short for a visible, longer-lasting result.

This is why the chains in some preparations are "cross-linked" – one can imagine it like small bridges between the chains. A cross-linker called BDDE is usually used for this. The more cross-linked it is, the more stable, firm, and longer-lasting the gel becomes.

It's precisely this stability that makes the difference between a filler and a skin booster.

Cross-linked hyaluronic acid: the fillers

Cross-linked hyaluronic acid is stable enough to provide shape. It's placed deeper and can build volume or define contours – for example, on the cheeks, chin, or lips. Because it breaks down more slowly, the result lasts several months to over a year.

The purpose here is a physical one: something is being filled out or shaped. It is not primarily about the quality of the skin's surface, but about the structure underneath.

Uncrossed-linked hyaluronic acid: the skin boosters

Non-cross-linked hyaluronic acid is more liquid and is not used for filling, but for so-called biorevitalization. It is injected into the skin in a widespread and superficial manner, distributing finely in the tissue and providing intensive moisture. The aim is a fresher, smoother complexion – not volume.

Because it breaks down more quickly, it is used in short courses and refreshed regularly. A well-known skin booster principle is stabilised, but not BDDE-crosslinked hyaluronic acid, which is produced via a special heat process and contains a high proportion of pure hyaluronic acid. In studies, non-crosslinked hyaluronic acid preparations measurably improved moisture, fine lines and the mechanical properties of the skin.

The second factor: molecular weight

In addition to networking, molecular weight, i.e. the size of the hyaluronic acid molecules, is decisive:

• High molecular weight hyaluronic acid is large. It tends to stay on the surface and form a moisture-binding film there.
• Low molecular weight hyaluronic acid is smaller and can penetrate deeper into the upper skin layers.

This is why the size is used differently in creams and injections. Why a hyaluronic cream still reaches its limits and what happens when hyaluronic acid only lies on the surface, we explain in the article. Does hyaluronic acid cream really work?.

Connected or not connected – the overview

And what's the use of aesthetics?

In our clinic, the focus is on skin quality, not volume. For moisture and micronutrients, we work with NCTF®, a non-networked hyaluronic acid complex with vitamins, amino acids, and other active ingredients. For the stimulation of cell renewal, we also rely on Polynucleotides – an active ingredient that takes a completely different path than hyaluronic acid.

What is beneficial for your skin depends on its condition and your goals. We'll clarify this in the free AURA 3D skin analysis.

Read on

• Polynucleotides or hyaluronic acid: which is better for skin quality?
• Does hyaluronic acid cream really work?
• What are polynucleotides?