Hyaluronic Acid (HA)

What is it?

Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan — a long, unbranched polysaccharide composed of repeating disaccharide units of D-glucuronic acid and N-acetyl-D-glucosamine. It is one of the most abundant components of the human extracellular matrix, with approximately 50% of the body's total HA residing in the skin. A single molecule of hyaluronic acid can bind up to 1,000 times its weight in water, making it the most powerful biological humectant known. In the dermis, HA maintains the hydrated gel-like matrix that provides structural support to collagen and elastin fibers, while in the epidermis it regulates moisture balance and supports barrier function. Skin HA content declines significantly with age — by age 50, the skin retains roughly half the HA it had at age 20 — contributing to visible dryness, loss of volume, and fine line formation. In skincare and aesthetic medicine, HA is available in multiple molecular weight forms: high molecular weight HA (>1,000 kDa) forms a hydrating film on the skin surface, medium molecular weight HA (100–1,000 kDa) penetrates the upper epidermis for deeper hydration, and low molecular weight HA (<100 kDa) can reach the dermis to stimulate cellular signaling. Crosslinked HA is used in dermal fillers for volume restoration, while non-crosslinked HA is used in skin boosters for hydration and quality improvement.

How It Works

1. 1

   Binds 1,000× Its Weight in Water

   A single HA molecule draws and holds enormous amounts of moisture at its site of application.

2. 2

   Molecular Weight Targets Depth

   High-MW HA hydrates the surface; low-MW HA penetrates deeper to signal cellular repair.

3. 3

   Carries PDRN into Tissue

   In skin boosters, HA acts as the diffusion matrix ensuring even distribution of PDRN fragments.

4. 4

   Stimulates Endogenous HA

   Low-MW HA activates CD44 receptors, nudging fibroblasts to produce more of their own HA.

Role in PDRN

In PDRN-based skincare and treatment protocols, hyaluronic acid serves as the ideal complementary ingredient. While PDRN activates fibroblasts through the adenosine A2A receptor to stimulate the skin's own production of HA and other glycosaminoglycans over weeks to months, exogenous HA provides immediate hydration from the first application. This creates a dual-timeline hydration strategy: HA addresses the symptom (dehydration) instantly, while PDRN rebuilds the cellular machinery that produces moisture naturally. Many professional PDRN skin booster injectables combine polynucleotides with non-crosslinked HA in a single formulation, leveraging HA as both a hydrating agent and a carrier matrix that improves the even distribution of PDRN throughout the treated tissue. In topical skincare, HA serums create a hydrated base layer that enhances the absorption and distribution of subsequently applied PDRN serums. The combination is universally well-tolerated, suitable for all skin types, and represents one of the most evidence-supported ingredient pairings in regenerative dermatology.

Clinical Data

Hyaluronic acid is among the most extensively studied ingredients in dermatology. A 2014 double-blind RCT published in the Journal of Drugs in Dermatology demonstrated that topical nano-hyaluronic acid significantly improved skin hydration, elasticity, and wrinkle depth over 60 days compared to placebo. Injectable non-crosslinked HA skin boosters have shown 30–40% improvements in skin hydration measured by corneometry after three treatment sessions. When combined with PDRN, clinical outcomes are superior to either ingredient alone — a 2021 comparative study showed that PDRN + HA skin booster treatment produced 28% greater improvement in skin elasticity and 35% greater improvement in hydration compared to HA skin booster alone at 12-week follow-up. The safety profile of HA is excellent across all formulations, with topical HA showing virtually zero irritation potential and injectable HA having decades of clinical safety data. As HA is a native component of human tissue, allergic reactions are exceedingly rare.

Product Formats in the Wild

Common ways this ingredient is delivered in clinical and consumer products.