Peptides AcademyHyaluronic Acid (HA)
How to Use
HA is universally compatible with all skincare actives including peptides, retinoids, vitamin C, and acids. It is often the base ingredient in peptide serums. Apply to damp skin for optimal moisture binding.
With peptides
HA is the ideal peptide vehicle. Many peptide serums (The Ordinary Matrixyl 10% + HA, Buffet) use HA as the base. The humectant matrix helps peptide molecules remain in contact with the skin surface longer.
Application tip
Apply HA-based products to damp skin (mist face with water first or apply within 60 seconds of cleansing). HA draws moisture from the nearest source — in humid environments that's the air, but in dry climates it can draw from the dermis if the skin surface is dry.
Molecular weight matters
Low-MW HA (<50 kDa) penetrates deeper and stimulates collagen. High-MW HA (>1,000 kDa) stays on the surface forming a moisture film. Multi-MW products deliver both benefits.
Best For
Where this entry is most relevant.
anti-aging
Dermal HA depletion is a hallmark of skin aging — it contributes to volume loss, reduced elasticity, and dehydration. Topical low-MW HA partially replenishes superficial dermal HA and signals fibroblasts to increase endogenous HA production.
skin-glow
Fully hydrated skin scatters light more uniformly, creating the 'glass skin' luminosity effect. HA's moisture-binding capacity creates this plumped, reflective surface within hours of application.
What is it?
A naturally occurring glycosaminoglycan that holds up to 1,000× its weight in water. In skincare, hyaluronic acid serves as both a hydration reservoir and a delivery vehicle for peptides — many peptide serums use HA as their base for enhanced penetration and moisture retention.
How It Works
- 1
Water binding
Each HA molecule binds hundreds of water molecules through hydrogen bonding, creating a hydrated gel matrix that plumps the skin and reduces the appearance of fine dehydration lines.
- 2
Size-dependent penetration
Low-MW HA (<50 kDa) penetrates the stratum corneum and reaches the viable epidermis, where it stimulates keratinocyte differentiation and signals fibroblasts. High-MW HA (>500 kDa) remains on the surface, forming a breathable moisture film.
- 3
CD44 receptor signaling
HA fragments of specific molecular weights bind the CD44 receptor on keratinocytes and fibroblasts, triggering downstream signaling that promotes wound healing, collagen synthesis, and cellular renewal.
- 4
Extracellular matrix scaffolding
In the dermis, HA forms part of the gel-like ground substance that supports collagen and elastin fibers. It provides the hydrated environment necessary for matrix protein assembly and cell migration.
Role
Humectant, delivery vehicle, extracellular matrix component
Evidence
Topical HA at low molecular weight (<50 kDa) has demonstrated improved skin hydration and reduced wrinkle depth in multiple RCTs. A 2011 study (Pavicic et al., J Drugs in Dermatology) showed significant wrinkle reduction and skin hydration with low-MW HA formulations at 0.1% over 60 days. Endogenous dermal HA decreases by ~50% from age 20 to 60.
Common Formats
How this shows up in practice.
The Ordinary Hyaluronic Acid 2% + B5
Serum
Multi-MW HA with panthenol; affordable HA base for peptide layering
The Ordinary Matrixyl 10% + HA
Peptide serum
HA serves as the delivery vehicle for Matrixyl 3000 + Synthe'6 peptides
SkinCeuticals Hyaluronic Acid Intensifier
Serum
Contains proxylane to boost endogenous HA synthesis alongside topical HA