Hyaluronic Acid

Water-binding actives that visibly plump, smooth and restore the skin's hydration reserves.

All Serums Hydragels Face Crémes Eye Crémes SPF Cleansers Masks
The Radiance Booster Serum The Radiance Booster Serum
The Radiance Booster Serum
The Radiance Booster Serum
The Radiance Booster Serum
The Radiance Booster Serum

The Radiance Booster Serum

A deeply hydrating serum.

$176.00

Add to Cart
Loading indicator
Tick Added to Cart

Suited to

["All skin"]
#1 The Strengthening Hydragel #1 The Strengthening Hydragel
#1 The Strengthening Hydragel
#1 The Strengthening Hydragel
#1 The Strengthening Hydragel
#1 The Strengthening Hydragel

#1 The Strengthening Hydragel

(Formerly #1 The Hydragel)

Hydrating gel for dehydrated skin.

100ml

$244.00

Add to Cart
Loading indicator
Tick Added to Cart

Frequently Asked Questions

What is Hyaluronic Acid?

Hyaluronic Acid is a humectant naturally found within the skin and connective tissues. It has a remarkable capacity to attract and hold up to one thousand times its weight in water, making it one of the most effective hydrating actives in skincare. Within RATIONALE formulations, it works to plump, hydrate, and visibly smooth the complexion across both AM and PM rituals.

What does Hyaluronic Acid do for skin?

Hyaluronic Acid attracts and binds water within the skin, providing immediate and sustained hydration. It works to plump the look of fine lines, refine the appearance of texture, and restore a luminous, well-hydrated complexion. Multi-molecular weight Hyaluronic Acid in our formulations delivers hydration at varying depths within the skin for comprehensive results.

Which RATIONALE formulations contain Hyaluronic Acid?

Hyaluronic Acid features across multiple formulations, with particular concentration in The Radiance Booster Serum, and also features in #1 The Strengthening Serum, #1 The Strengthening Hydragel, #4 The Nourishing Eye Crème, Beautiful Skin Superfluid and our Beautiful Balms. Our Skin Questionnaire can guide your selection based on hydration needs.

Is Hyaluronic Acid suitable for all skin types?

Yes. Hyaluronic Acid is universally well tolerated and suitable for all skin types, including sensitive, oily, dry, and combination skin. As a Skin Identical molecule, it integrates seamlessly into the skin's natural hydration system without compromising barrier function. It is especially beneficial for skin experiencing dehydration, climate change, travel, or hormonal transition.

Can I use Hyaluronic Acid with retinol or Vitamin C?

Yes. Hyaluronic Acid layers effectively with all RATIONALE actives, including Vitamin C (AM ritual) and retinol (PM ritual). It is often used to support hydration and comfort when introducing more active formulations. Apply Hyaluronic Acid-rich formulations after cleansing and before treatment serums.

When should I apply Hyaluronic Acid?

Hyaluronic Acid is suitable for both AM and PM use. For optimal hydration, apply to slightly damp skin after cleansing, then layer with treatment serums and finish with a crème, hydragel, or gelcrème to help lock hydration in. Daily use supports cumulative improvement in skin hydration and the appearance of plumpness.

What is the difference between hydration and moisturisation?

Hydration refers to the skin's water content and is supported by humectants such as Hyaluronic Acid. Moisturisation refers to lipid replenishment, supported by Ceramides, Lipids, and crème formulations. Healthy skin requires both: humectants to draw water in, and lipids to seal hydration within the barrier.

Hyaluronic Acid is one of the few skincare actives whose function and benefit is immediately perceptible.

Applied to the skin, its visible effects, plumpness, softness, a visible reduction in the appearance of fine lines, can be seen and felt within minutes. It is a powerful humectant, capable of holding up to 1,000 times its own weight in water and making it the most effective water-binding molecule available to skincare science.

With this in mind, we recommend applying a hyaluronic acid formulation to damp skin. This creates an immediate water reserve for it to draw upon to help lock moisture in.

Found naturally in the epidermis and dermis, its presence in skin declines significantly with age, contributing to the loss of volume and suppleness that defines the visible ageing process. This is where topical supplementation via high-performance skincare becomes vital to support long-term skin health goals.

The science of Hyaluronic Acid formulation lies in molecular weight. High-molecular-weight HA works at the surface, forming a film that visibly plumps and retains moisture.
Low-molecular-weight HA penetrates more deeply, replenishing hydration reserves within the skin's lower layers. The most sophisticated formulations combine both to deliver immediate surface benefit alongside deeper, more lasting hydration.

RATIONALE's hydration ritual is anchored by #1 The Strengthening Hydragel — a lightweight, water-binding formulation that visibly plumps and replenishes with immediate effect, suited to combination and dehydrated skin types in themorning ritual.

In the evening, #6 The Rejuvenating GelCrème delivers hydration in a revitalising gel texture that partners Hyaluronic Acid with Bakuchiol and DNA Repair Enzymes — pairing the skins hydration needs with its renewal requirements in a single formulation.

For a serum solution, consider The Radiance Booster Serum from The Gifting Collection, which offers hyaluronic acid in a water light delivery. Layered under heavier gels and creams, it adds additional hydration benefits without weighing skin down.


For a hydration ritual personalised to your skin goals, take our Skin Questionnaire or explore the Nourishing Collection.

Skin Questionnaire