Hyaluronic acid (HA) is a naturally occurring, water-loving molecule found throughout the body—in the skin, eyes and joints—where its main job is to hold moisture and cushion tissue. In medical aesthetics it is best known as the key ingredient in most modern dermal fillers: because HA is made by the body, binds large amounts of water and can be dissolved if needed, it has become the material of choice for restoring volume and refining facial contours.

At a glance

What it is: A naturally occurring sugar molecule (a glycosaminoglycan) that binds water
Where it’s found: Naturally in skin, eyes and joints; a major part of the skin’s support matrix
Signature trait: Holds a remarkable amount of water for its weight—giving hydration and volume
In aesthetics: The most common type of dermal filler for lips, cheeks and facial contour
Key advantage: HA fillers are reversible—they can be dissolved with the enzyme hyaluronidase
Also in skincare: A popular topical humectant in serums and moisturisers for surface hydration

What is hyaluronic acid?

Hyaluronic acid is a glycosaminoglycan—a long sugar-based molecule—that occurs naturally in the skin, connective tissue, eyes and the fluid that lubricates our joints, where it is a major component of the extracellular matrix.^[1] Its defining feature is an extraordinary ability to attract and hold water: it can bind many times its own weight in moisture, which is what lets it swell, create volume and give tissue its plump, cushioned quality.^[1][2] The collagen and elastin in skin provide structure and stretch, while HA fills the spaces between them with hydration. The body’s own supply gradually declines with age, contributing to drier, less plump skin over time.^[2]

Why HA is ideal for dermal fillers

Several qualities make hyaluronic acid the go-to material for dermal fillers. Because it is identical across all living tissue, HA is highly biocompatible—the body recognises it, so allergic reaction is rare. Its water-binding, gel-like nature adds soft, natural-feeling volume exactly where it is placed.^[1] And crucially for safety, an HA filler is reversible—it can be dissolved on demand (see below), unlike most other filler materials. Natural, volumising and reversible: that is why HA is the most widely used filler in aesthetics.

From natural HA to long-lasting filler: cross-linking

Pure hyaluronic acid in the body breaks down within a day or two, so on its own it would be far too short-lived to use as a filler. To solve this, manufacturers “cross-link” the HA—chemically bonding the chains together into a stable gel that the body breaks down much more slowly.^[1] The degree of cross-linking is what largely determines a filler’s firmness and how long it lasts, and it is why different HA products are formulated for different jobs: softer, more fluid gels for delicate areas like the lips and under-eyes, and firmer, more structured gels for building cheek or jawline definition. As the filler slowly degrades, water gradually replaces the gel while volume is maintained—a process called isovolumetric degradation.^[1]

What HA fillers treat

HA fillers are used across the face to restore volume and refine shape: plumping and defining the lips and the Cupid’s bow, restoring cheek volume, softening folds around the nose and mouth, improving hollowing under the eyes, and adding definition to the jawline and chin.^[2] Because HA is so versatile and adjustable, an experienced injector can tailor the product and technique to each area. At Revel, HA fillers are offered through our face treatments, including dedicated dermal filler for lips. Other filler types—such as calcium hydroxylapatite and poly-L-lactic acid—work differently and are chosen for specific goals.

How long they last — and the reversibility advantage

How long an HA filler lasts depends on the product, the area and the individual, but effects commonly last in the range of several months to well over a year as the gel is gradually and naturally absorbed.^[1] The standout safety feature of HA is that it can be dissolved: the enzyme hyaluronidase breaks down both natural and injected hyaluronic acid, so an unwanted result can be softened or reversed, and—critically—a serious complication can be treated quickly.^[1] This built-in “undo” is a major reason HA is favoured, especially for those new to fillers.

Hyaluronic acid in skincare

Beyond injectables, HA is a hugely popular ingredient in topical skincare, where it acts as a humectant—drawing water to the surface layers of the skin to leave it looking smoother, plumper and more hydrated.^[2] It’s a lovely part of a hydrating routine, but worth keeping in perspective: a topical serum works at the surface and cannot replace the deep, structural volume that an injected filler provides. The two do different jobs.

Safety, and HA fillers in Canada

HA fillers have a strong safety record, and most side effects are mild and temporary—bruising, swelling or tenderness at the site. As with any dermal filler, the most serious (though uncommon) risk is injection into or compression of a blood vessel, which is why skilled technique matters—and why HA’s reversibility with hyaluronidase is such a valuable safeguard. In Canada, dermal fillers are regulated as licensed medical devices; only Health Canada–authorized products should be used, administered by a qualified professional.^[3] This entry is educational and does not replace an individual clinical assessment.

Related glossary terms

Clinical & editorial sources

Gupta RC, et al. Hyaluronic Acid. StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing. NBK482440
Cleveland Clinic. Hyaluronic Acid: What It Is, Benefits, How To Use & Side Effects. clevelandclinic.org
Health Canada. Information Update: Needle-free dermal filler devices are not authorized in Canada and may pose health risks (dermal fillers regulated as licensed medical devices). Government of Canada. recalls-rappels.canada.ca

This glossary entry provides general educational information and does not replace an individual clinical assessment or medical advice.

Clinically reviewed by: Leah Zawawi, RPN | Medical Aesthetics & Injectables.

Last reviewed: August 2026.