Hyaluronic Acid —
Effects, Molecular Weight & The Truth
Hyaluronic acid is in almost every moisturizing product. But what's really behind it? Its mechanism of action, molecular weight, and what matters for its application — scientifically explained.
What Hyaluronic Acid is
Hardly any active ingredient is as ubiquitous in modern skincare as hyaluronic acid. It can be found in serums, creams, toners, and masks — often multiple times per routine, in different formulations and concentrations. Yet, despite its omnipresence, fundamental questions about its mechanism of action are far less known than marketing promises would suggest.
Hyaluronic acid is an endogenous polysaccharide found in the skin, connective tissue, and synovial fluid. Its primary biochemical task: water binding and structural stabilization. What happens when applied topically — and why molecular weight plays a crucial role — is the core of this article.
HA can bind water
is found in the skin
begins to decline
Mechanism of Action
Topically, hyaluronic acid primarily acts as a humectant — an active ingredient that attracts and retains moisture in the skin's surface. However, the way it does this critically depends on its molecular weight.
High molecular weight hyaluronic acid (over 1 MDa) forms a moisture-binding film on the skin's surface. It does not penetrate into deeper layers but can reduce transepidermal water loss (TEWL) and provides an immediate feeling of softness.
Low molecular weight HA fragments (below 50 kDa) can penetrate deeper into the epidermis. The literature discusses whether these smaller fragments can also stimulate fibroblasts in the dermis — the data available is more nuanced than often communicated.
Hyaluronic acid interacts with proteoglycans in the skin and influences the structure of the extracellular matrix. As part of the natural moisturizing factor (NMF), it contributes to barrier homeostasis — an effect that can be supported by the right formulation environment.
Hyaluronic acid is a reliable, well-tolerated active ingredient — but not a panacea. Its strength lies in water binding, not in structural changes to the skin. Understanding this allows for its sensible use: as a moisture anchor, not an anti-aging miracle.
In dry indoor climates (heating, air conditioning), high molecular weight hyaluronic acid on dry skin without subsequent sealing can have the opposite effect: it draws moisture from deeper skin layers to balance the concentration gradient. The combination with an occlusive formulation is therefore particularly crucial during the heating season.
Forms in the Routine
Hyaluronic acid appears in modern cosmetics in several different roles — depending on its molecular weight, modification, and formulation context. Knowing these variants helps to classify product claims and choose the appropriate form for one's own routine.
Many modern serum formulations combine several molecular weights simultaneously — with the aim of achieving both superficial and deeper moisturizing effects. In practice, this approach is widely used, although proof of additive benefit over single-weight formulations is still pending.
Hyaluronic acid is a humectant — it needs moisture to bind it. On dry skin in a dry environment, it can have the opposite effect, drawing moisture from deeper skin layers. Applying it to slightly damp skin and sealing it with a cream is crucial.
Hyaluronic acid is often used as a formulation aid — it improves texture, increases spreadability, and can act as a carrier for other active ingredients like vitamin C or niacinamide without affecting their stability.
The sodium salt of hyaluronic acid (Sodium Hyaluronate) is the most common form in INCI lists. It is more water-soluble and stable than free hyaluronic acid — and functionally equivalent at the same molecular weight. Not a quality feature, but a standard practical solution for formulation.
What this means for skincare
Hyaluronic acid unfolds its effects not in isolation, but in interaction with the formulation environment, application technique, and skin barrier. The correct integration into the routine largely determines whether the active ingredient's potential is utilized or remains unused.
- Apply to slightly damp skin
- Seal afterwards with cream or oil
- Combination with ceramides for barrier support
- Multi-weight formulations for differentiated effects
- Consistent application morning and evening
- On completely dry skin in a very dry environment
- Without subsequent sealing in cold air
- Overestimated expectations of structural change effects
- Too low a concentration below the functional threshold
»Hyaluronic acid is not an anti-aging miracle — but an indispensable moisture anchor, if you know the rules by which it works.«
Field Notes: TEWL & the Skin Barrier · Field Notes: Skin Barrier
The NATURFACTOR® Porcelain Skin Serum integrates double-concentrated hyaluronic acid as part of the Bioactive Infusion Complex™ — formulated for optimal moisture retention in the Day Rhythm.
A Note on Dermatology
Cosmetic hyaluronic acid formulations can support skin moisture but do not replace dermatological treatment. For persistent dry skin, barrier disorders, or diagnosed skin conditions such as atopic dermatitis, a specialist dermatological assessment should be sought. The efficacy of topical hyaluronic acid varies individually and depends on skin type, climate conditions, and formulation.
Frequently Asked Questions
Is more expensive hyaluronic acid more effective?
Not necessarily. The key factors are molecular weight, concentration, and the overall formulation — not the price. Sodium Hyaluronate in an inexpensive formulation can be just as effective as in a luxury product if the other parameters are correct.
Can hyaluronic acid permanently smooth wrinkles?
Topical hyaluronic acid can temporarily improve the appearance of fine lines through hydration — a "plumping effect". Permanent structural changes in the dermis due to topical application are not proven in the literature. This distinction is important for realistic expectations.
How much hyaluronic acid is enough?
In clinical studies, concentrations between 0.1% and 2% are typically used. More is not automatically better — the texture and tolerability of the overall formulation play just as important a role as the pure concentration of the active ingredient.
Is hyaluronic acid suitable for all skin types?
Yes — hyaluronic acid is considered very well tolerated and is suitable for all skin types, including sensitive and acne-prone skin. It is non-comedogenic and rarely causes irritation in the literature.
- Papakonstantinou E. et al. (2012). Hyaluronic acid: A key molecule in skin aging. Dermato-Endocrinology, 4(3), 253–258.
- Ganceviciene R. et al. (2012). Skin anti-aging strategies. Dermato-Endocrinology, 4(3), 308–319.
- Bukhari S.N.A. et al. (2018). Hyaluronic acid, a promising skin rejuvenating biomedicine: A review. Chemical Biology & Drug Design, 91(5), 1–15.
- Brandt F.S. & Cazzaniga A. (2008). Hyaluronic acid fillers: Indications and practical approach. Clinics in Plastic Surgery, 35(1), 47–55.
