Hydrators vs Moisturisers: What’s the Difference? And Which Does Your Skin Really Need?

katekelso0
7 days ago
3 min read

Have you ever wondered whether your skin needs a hydration or a moisturiser? The two terms are often used interchangeably, but they actually describe very different processes within the skin.

Understanding the distinction helps you choose the right products and get the best from your in-clinic treatments.

Hydration vs Moisture — What’s the Difference?

Hydration refers to the water content within your skin, especially in the epidermis and dermis. Well hydrated skin functions optimally, maintaining elasticity, radiance and barrier integrity.
Moisture refers to the skin’s ability to retain that water and prevent transepidermal water loss (TEWL). Moisturisers help seal in hydration and reinforce the barrier.

Think of hydration as “adding water” and moisturising as “keeping it in.” Both are essential for healthy, resilient skin.

Why This Matters More as We Age

As skin matures, several biological changes affect both hydration and moisture retention:

Hyaluronic acid (HA) and glycosaminoglycans decline, reducing the skin’s ability to bind and hold water.
Barrier lipids such as ceramides, cholesterol and fatty acids diminish, allowing more water to escape.
Collagen and elastin fibres degrade, weakening internal support and affecting hydration balance.

The result is skin that looks and feels dry, dull or tight, with fine lines appearing more prominent.

Restoring both internal hydration and barrier integrity improves comfort, radiance and elasticity.

How Hydrators Work

Topical hydrators increase water content in the upper skin layers using humectants such as glycerin, urea and hyaluronic acid.

These attract and bind water molecules, plumping and smoothing the surface.

However, because the outer layer of the skin (the stratum corneum) is such an effective barrier, topical hydrators can only reach the surface and near-surface layers.

That’s why many patients notice a quick glow but limited long-term change, and why deeper injectable options can make such a difference.

How Moisturisers Work

Moisturisers focus on preventing water loss and restoring the skin barrier. They combine:

Occlusives (such as dimethicone or petrolatum) to create a film that prevents evaporation.
Emollients (like squalane and triglycerides) to smooth and soften.
Barrier-repair ingredients (ceramides, cholesterol, fatty acids) to restore lipid balance and reduce TEWL.

For mature or dry skin, the best approach is a combination: apply a hydrating serum first, then follow with a barrier-repairing moisturiser to seal it in.

The Science of Deep Hydration

Skin Boosters and Polynucleotides

For those wanting to go beyond topical care, skin boosters and polynucleotide treatments provide deep, biologically active hydration and tissue renewal from within.

Skin Boosters (Profhilo, Redensity I, Seventy Hyal)

These treatments deliver stabilised hyaluronic acid into the dermis, where it attracts water, stimulates fibroblasts, and remodels collagen and elastin.

Hyaluronic acid acts as a hydrophilic scaffold, supporting long-term hydration and improving skin firmness, elasticity and luminosity.¹⁻³

Each brand has subtle differences:

Profhilo uses both high- and low-molecular-weight HA to stimulate bio-remodelling.
Redensity I combines HA with antioxidants, amino acids and minerals.
Seventy Hyal focuses on rapid hydration and restoring radiance.

Polynucleotides (Newest)

Polynucleotides (PNs) are naturally derived DNA fragments that work differently to hyaluronic acid.

They:

Bind water molecules to form a hydrated gel within the dermis.
Stimulate fibroblasts to produce new collagen and elastin.
Offer antioxidant and anti-inflammatory benefits, improving tone and texture.⁴

Newest combines hyaluronic acid with polynucleotides, giving the dual benefit of deep hydration and cellular repair.

The HA delivers immediate hydration, while the polynucleotides promote long-term rejuvenation by improving the skin’s natural water-holding capacity and structure.

It’s an excellent choice for skin that feels crepey, dehydrated or environmentally stressed, perfect for subtle rejuvenation without added volume.

Combining Surface and Structural Hydration

Healthy, luminous skin needs both surface and deep hydration:

Surface care:
Use a humectant-based serum to draw in water, followed by a lipid-rich moisturiser to retain it.
Structural care:
Support the dermal matrix with injectable treatments such as Profhilo, Redensity I, Seventy Hyal, or Newest polynucleotides.
Consistency:
Topical skincare maintains the surface; in-clinic treatments strengthen the foundation for lasting results.

The Takeaway

Hydration and moisturisation are related but distinct.

Topical products improve the skin’s surface, while injectable treatments like Profhilo, Redensity I, Seventy Hyal, and Newest restore deep hydration and structure.

Together, they transform the skin from dull and tight to supple, luminous and resilient — supporting not just how it looks, but how it behaves.

References

Rawlings A.V. Stratum corneum hydration and barrier function. Int J Cosmet Sci. 2004.
Draelos Z.D. Topical skincare management of aging skin. J Cosmet Dermatol. 2018; 17(4): 687–694.
Fink A.F. et al. Bio-remodelling effects of injectable hyaluronic acid: a review. Plast Reconstr Surg. 2017; 140(1): 103-111.
Papakonstantinou E. et al. Polynucleotides in dermatology: mechanisms and clinical applications. Clin Cosmet Investig Dermatol. 2023; 16: 123-137.