• O Cosmedics 4D Hyaluronic Serum hydrating face serum with four forms of Hyaluronic Acid for dehydrated, dry and sensitive skin.
  • O Cosmedics 4D Hyaluronic Serum 4D Hyaluronic Acid technology for multi-layer hydration and plumper, smoother-looking skin.
  • O Cosmedics 4D Hyaluronic Serum for dehydration, fine lines and skin barrier support with long-lasting multi-layer moisture.
  • O Cosmedics 4D Hyaluronic Serum lightweight water-gel Hyaluronic Acid serum for deep hydration, softness and skin bounce.
  • O Cosmedics 4D Hyaluronic Serum multi-layer hydration serum with four forms of Hyaluronic Acid for plumper, smoother and deeply hydrated skin.
  • O Cosmedics 4D Hyaluronic Serum corrective hydrating serum for dehydrated skin alongside the O Cosmedics serum collection.
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O Cosmedics

O Cosmedics 4D Hyaluronic Serum 30ml

O Cosmedics 4D Hyaluronic Serum 30ml

$99.00 AUD
$99.00 AUD
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O Cosmedics 4D Hyaluronic Serum is an advanced Hyaluronic Acid serum designed to restore hydration to dry, dehydrated and moisture-depleted skin. Four forms of Sodium Hyaluronate work at different levels to attract, hold and retain water, helping skin feel softer, more supple and comfortably hydrated. 

Its 4D Hyaluronic Acid technology combines Sodium Hyaluronate Crosspolymer, Sodium Hyaluronate, Sodium Acetylated Hyaluronate and Hydrolyzed Sodium Hyaluronate. Together, they create a multidimensional moisture network that supports both immediate and longer-lasting hydration while helping reduce water loss, improve visible elasticity and restore bounce. 

The lightweight serum layers easily beneath corrective skincare and moisturiser without adding heaviness to the routine. Suitable for all skin types, it is particularly useful when dehydration is contributing to tightness, dullness, roughness or fine lines that become more noticeable as the skin loses moisture.

Product Size: 30ml

SKIN DEEP MEDISPA EXPERT VERDICT
Our rating: 4.9/5
O Cosmedics 4D Hyaluronic Serum is one I reach for when dehydration is having a noticeable effect on how the skin looks and feels. I particularly like it when skin feels tight, looks flat or lacks bounce, or when fine lines are becoming more obvious because the skin simply isn't holding enough water. What appeals to me about this formula is that the four forms of Hyaluronic Acid have different roles rather than relying on one form to provide all of the hydration. It also gives me a very straightforward way to improve hydration without interfering with whatever corrective work we're already doing for pigmentation, breakouts or ageing.

BEST FOR
Dry/Dehydrated • Dull • Sensitive • Fine Dehydration Lines • Loss of Plumpness

I wouldn't automatically add 4D Hyaluronic Serum to a routine where hydration is already well managed. If pigmentation, congestion or more advanced signs of ageing are the priority, I'd rather put the corrective focus there. I choose this serum when dehydration itself needs treating, not simply because Hyaluronic Acid is a popular skincare ingredient.

Reviewed by: Diana / Founder & Head of Clinical Therapies, Skin Deep Medispa, Armadale

🔥 OUR HOT TIP
Apply 4D Hyaluronic Serum while your skin is still slightly damp after cleansing rather than waiting until it feels completely dry. I find this particularly helpful with dehydrated skin because Hyaluronic Acid works by attracting and binding water. Follow with your moisturiser to help keep that hydration in the skin.

Not sure if it’s right for your skin? Ask A Skin Deep Medispa Therapist

What We Love

✓ Four forms of Hyaluronic Acid provide a more comprehensive approach to hydration than a single-form Hyaluronic Acid serum.
✓ Helps reduce water loss, supporting longer-lasting moisture when skin struggles to stay comfortably hydrated.
✓ Restores visible plumpness and bounce, particularly when dehydration is making skin appear flat or depleted.
✓ Softens the appearance of dehydration lines by replenishing the moisture that helps keep skin smooth and supple.
✓ Lightweight and highly layerable, making it easy to add hydration alongside existing corrective skincare.

Key Ingredients

✓ Sodium Hyaluronate Crosspolymer - An ultra-high molecular weight form that creates a breathable moisture shield at the skin's surface, helping reduce water loss and support prolonged hydration.
✓ Sodium Hyaluronate- A high molecular weight form that holds water at the skin's surface, helping improve softness, smoothness and suppleness.
✓ Sodium Acetylated Hyaluronate - An adhesive form with strong affinity for the outer skin layers, supporting sustained surface hydration and a softer skin feel.
✓ Hydrolyzed Sodium Hyaluronate - An ultra-low molecular weight form that supports hydration deeper within the skin, helping improve visible elasticity, bounce and plumpness.

Ingredients: Aqua, Pentylene Glycol, Ethoxydiglycol, Glycerin, Propanediol, Sodium Hyaluronate Crosspolymer, Sodium Hyaluronate, Sodium Acetylated Hyaluronate, Hydrolyzed Sodium Hyaluronate, Ethylhexylglycerin, Heptyl Glucoside, Sodium Benzoate, Potassium Sorbate, Sodium Levulinate, Citric Acid.

Free from parabens, sulfates, petrochemicals and mineral oils, with no artificial colours, harsh preservatives or harsh synthetic fragrances. Vegan-friendly, gluten-free and cruelty-free. The formula is emulsifier-free and biomimetic.

How To Use

Apply morning and/or evening to freshly cleansed skin.

Dispense 1 pump onto fingertips and smooth over the face and neck, including around the eye area. Allow to absorb before following with additional O Cosmedics serums and moisturiser.

In the morning, always finish with O Cosmedics Mineral Pro SPF.

Pair It With

O Cosmedics Gentle Antioxidant Cleanser

O Cosmedics Comfort Cream

O Cosmedics 3 In 1 Fruit Peel Mask

FAQs

What is O Cosmedics 4D Hyaluronic Serum best for?
We recommend O Cosmedics 4D Hyaluronic Serum when skin is showing recognisable signs of dehydration such as tightness, dullness, roughness, reduced bounce or fine dehydration lines. It can be used by all skin types, including sensitive skin, but it earns its place in a routine when hydration genuinely needs additional attention.

What is the difference between O Cosmedics 4D Hyaluronic Serum and the original 3D Hyaluronic Serum?
O Cosmedics 4D Hyaluronic Serum is the upgraded formula that replaces O Cosmedics 3D Hyaluronic Serum. The major change is the move from the previous multi-weight system to four distinct forms of Sodium Hyaluronate, each selected for how it behaves at a different level of the skin. If you previously used 3D Hyaluronic Serum, 4D is its current replacement.

Why does O Cosmedics 4D Hyaluronic Serum contain four types of Hyaluronic Acid?
Different forms of Hyaluronic Acid behave differently according to their molecular size and structure. O Cosmedics combines four forms so the formula can support moisture retention at the surface while also addressing deeper hydration, elasticity and bounce. We see this as the main reason to choose 4D over a more basic single-form Hyaluronic Acid serum.

Is O Cosmedics 4D Hyaluronic Serum suitable for sensitive skin?
Yes. Its hydration-focused formula makes it a useful option when sensitive skin is also dehydrated. If sensitivity is being driven by an actively compromised barrier, persistent redness or significant reactivity, however, we may prioritise O Cosmedics B12 Smart Serum or a more recovery-focused routine rather than assuming additional hydration alone will address the problem.

Can I use O Cosmedics 4D Hyaluronic Serum with Retinol or Vitamin C?
Yes. This is actually one of the reasons we like having a dedicated Hyaluronic Acid serum available. It can provide additional hydration alongside Vitamin A, Vitamin C and other corrective serums without trying to perform the same corrective job. We tailor the rest of the routine to your skin tolerance and the actives you're using.

Do I still need a moisturiser after O Cosmedics 4D Hyaluronic Serum?
For most dehydrated or dry skins, yes. A Hyaluronic Acid serum and a moisturiser perform different roles. We use O Cosmedics 4D Hyaluronic Serum as the concentrated water-binding step, then choose an O Cosmedics moisturiser according to how much additional moisture, nourishment and barrier support the skin requires.

Can oily or breakout-prone skin use O Cosmedics 4D Hyaluronic Serum?
Yes. Dehydration and oiliness can occur at the same time, so an oily skin type doesn't automatically mean the skin is adequately hydrated. The lightweight formula can be useful when oily or breakout-prone skin feels tight or dehydrated without adding a rich moisturising layer. We would still treat congestion or breakouts separately if they are the primary concern.

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★★★★★

“My skin is combination but gets really dehydrated, so I wanted hydration without a heavy cream. This sinks in quickly and my skin feels much more comfortable through the day. It also sits beautifully under makeup.”

Sophie, Brisbane QLD

★★★★★

“The biggest difference for me has been how much plumper my skin looks. I was noticing little lines around my eyes and forehead whenever my skin was dry, and they look much softer now. No sticky finish either.”

Natalie, Bendigo VIC

★★★★★

“I use Vitamin A at night and wanted something simple to help with the dryness without adding another active treatment. This has fitted in perfectly. My skin feels softer and I don't get that tight feeling after cleansing anymore.”

Claire, Wollongong NSW