Hyaluronic acid: which one to choose and why weight matters

Hyaluronic acid is everywhere. In serums, creams, masks, and supplements. It's the best-selling moisturizing active ingredient in the world. And yet, the majority of products that feature it don't deliver on their promises.

The reason: hyaluronic acid is not a single molecule. It's a family of molecules whose effectiveness depends entirely on their size — and this size is almost never indicated on labels.

Hyaluronic acid can hold up to 1000 times its weight in water. But it still needs to be where it's supposed to be.

What hyaluronic acid truly is

Hyaluronic acid is a glycosaminoglycan naturally present in the dermis, joints, and connective tissues. In the skin, it plays a major role in tissue hydration and maintaining dermal volume by capturing and retaining water in the extracellular matrix.

Its production by the body declines from the age of twenty and drops more sharply from the age of 40. It is this progressive decrease that contributes to loss of volume, the appearance of fine lines, and loss of radiance associated with skin aging.

Molecular weight: the variable everyone ignores

This is the key point that most brands don't explain — because it reveals why their products are often less effective than advertised.

High molecular weight hyaluronic acid (greater than 1000 kDa) is a large molecule. It is too voluminous to penetrate the skin barrier. It remains on the surface, forms a protective film, retains water in the epidermis, and visually smooths superficial fine lines. The effect is immediate and comfortable, but it disappears with washing. This is surface hydration.

Low molecular weight hyaluronic acid (between 50 and 300 kDa) is a smaller molecule. It can penetrate into the deeper layers of the epidermis, stimulate fibroblast activity, and contribute to more lasting hydration. Its effect is less immediate but more structural.

Very low molecular weight molecules (less than 20 kDa) require a caution: some studies indicate that they could cause a local inflammatory reaction. Low and high molecular weights remain the most documented and widely used forms.

In practice, the best hyaluronic acid serums combine several molecular weights to act both on the surface and in depth. A product that states "hyaluronic acid" without specifying the molecular weight probably only hydrates the surface.

Concentration: the other variable brands hide

For a hyaluronic acid treatment to produce a significant effect, the concentration must be sufficient. For a moisturizing cream, a concentration around 1% is the threshold from which effects are documented. For a concentrated serum, it can go up to 2%.

A product that lists sodium hyaluronate (INCI name for hyaluronic acid) at position 15 on a list of 20 ingredients probably contains less than 1% active ingredient. This is insufficient to go beyond surface hydration.

How to apply it to maximize its effectiveness

Hyaluronic acid is a humectant: it attracts water present in its environment. On dry skin in a low-humidity environment, it can paradoxically draw water from the deeper layers to the surface and evaporate it. The application rule is simple: apply to slightly damp skin, then immediately seal with a cream or a light occlusive. This sequence maximizes water retention and prevents the opposite effect.

Oral hyaluronic acid: a complementary approach

Oral hyaluronic acid supplementation with low molecular weight is documented to improve skin hydration and reduce wrinkle depth after 8 to 12 weeks. Ingested hyaluronic acid reaches the bloodstream and the deeper layers of the dermis from within, where topical treatments cannot always go. Gastro-resistant capsule forms protect the molecule from digestive enzymes for better bioavailability.

The Paradermia approach

Our pharmacist selects hyaluronic acid products based on their actual formulation: molecular weight, concentration, and compatibility with other active ingredients in the routine. The goal is to offer you hydration that truly works, both on the surface and in depth, integrated into a coherent protocol.

Frequently asked questions

Can I find truly effective hyaluronic acid products on Paradermia?
Yes. Each referenced product has been audited for its formulation: molecular weight of the hyaluronic acid used, probable concentration according to its position in the INCI list, and suitability for the skin profile for which it is recommended. You are not choosing a product that displays hyaluronic acid on its packaging — you are choosing a product that actually contains it at a useful dose.

Is hyaluronic acid suitable for all skin types?
Yes. It is one of the best-tolerated active ingredients in cosmetics, with no known contraindications for healthy skin. It is particularly useful for dehydrated skin, mature skin, and as support for the skin barrier for sensitive skin or skin undergoing retinization.

Should it be applied morning and evening?
Yes, both applications are relevant. In the morning, it supports hydration and the barrier before exposure to external factors. In the evening, it supports nocturnal cell regeneration. The key is to apply it to slightly damp skin and seal it with a moisturizer.