Medik8 C-Tetra Advanced bottle displayed on a clean white background with translucent serum droplets, highlighting its lightweight gel-serum texture.
Close-up of a woman with radiant, even-toned skin, with text highlighting how C-Tetra Advanced defends against premature ageing by improving brightness, wrinkles, and skin texture.
Before and after close-up of a participant’s skin over 7 days, demonstrating visibly smoother skin texture and refined appearance.
Smiling woman with radiant skin and a swipe of Medik8 C-Tetra Advanced serum on her cheek, emphasising 0% barrier disruption for gentle yet effective brightening.
An infographic titled "Scientifically Proven Reduction in Oxidative Stress*" set against a warm orange background. It compares two microscopic cross-sections of skin (epidermis and dermis). The left image, labeled "SKIN EXPOSED TO ENVIROMENTAL STRESSORS," shows bright yellow glowing areas indicating harmful oxidative stress. The right image, labeled "SKIN EXPOSED TO ENVIROMENTAL STRESSORS WITH C-TETRA ADVANCED," shows significantly darker tissue, demonstrating a reduction in oxidative stress.
Molecular representation of key ingredients in Medik8 C-Tetra Advanced, with text highlighting 20% Vitamin C, Phyto Exosomes, Acetyl Zingerone, Hyaluronic Acid, and N-Acetyl Glucosamine (NAG) for brightening, hydration, and skin barrier support.
Before and after comparison of a participant’s skin over 7 days, showing visibly brighter skin with improved radiance and even tone.
An infographic titled "How To Layer" outlines an AM skincare routine on an orange background. It highlights the "Vitamin C" step featuring C-Tetra Advanced, positioned between "Cleanse" (Surface Radiance Cleanse), "Tone" (Press & Glow), and "Moisturiser & SPF" (Advanced Day Ultimate Protect).
"MEET YOUR VITAMIN C" chart on an orange gradient background with hexagonal graphics. Four Medik8 serums are shown. From left: C-Tetra dropper bottle (7% Vitamin C, for sensitive skins or beginners), C-Tetra Luxe dropper bottle (14% Vitamin C, for dry skin), C-Tetra Advanced pump bottle (20% Vitamin C, for normal, combination, and oily skin), and Super C Ferulic dropper bottle (30% Ethylated L-Ascorbic Acid, for experienced users).
A 30mL amber pump bottle of Medik8 C-Tetra Advanced standing next to its white cardboard carton against a clean white background. Text on the bottle and carton reads "20% Vitamin C Gel-Serum," "Brighten & Age Defence," and "with Phyto Exosomes."
Medik8 C-Tetra Advanced bottle displayed on a clean white background with translucent serum droplets, highlighting its lightweight gel-serum texture.
Close-up of a woman with radiant, even-toned skin, with text highlighting how C-Tetra Advanced defends against premature ageing by improving brightness, wrinkles, and skin texture.
Before and after close-up of a participant’s skin over 7 days, demonstrating visibly smoother skin texture and refined appearance.
Smiling woman with radiant skin and a swipe of Medik8 C-Tetra Advanced serum on her cheek, emphasising 0% barrier disruption for gentle yet effective brightening.
An infographic titled "Scientifically Proven Reduction in Oxidative Stress*" set against a warm orange background. It compares two microscopic cross-sections of skin (epidermis and dermis). The left image, labeled "SKIN EXPOSED TO ENVIROMENTAL STRESSORS," shows bright yellow glowing areas indicating harmful oxidative stress. The right image, labeled "SKIN EXPOSED TO ENVIROMENTAL STRESSORS WITH C-TETRA ADVANCED," shows significantly darker tissue, demonstrating a reduction in oxidative stress.
Molecular representation of key ingredients in Medik8 C-Tetra Advanced, with text highlighting 20% Vitamin C, Phyto Exosomes, Acetyl Zingerone, Hyaluronic Acid, and N-Acetyl Glucosamine (NAG) for brightening, hydration, and skin barrier support.
Before and after comparison of a participant’s skin over 7 days, showing visibly brighter skin with improved radiance and even tone.
An infographic titled "How To Layer" outlines an AM skincare routine on an orange background. It highlights the "Vitamin C" step featuring C-Tetra Advanced, positioned between "Cleanse" (Surface Radiance Cleanse), "Tone" (Press & Glow), and "Moisturiser & SPF" (Advanced Day Ultimate Protect).
"MEET YOUR VITAMIN C" chart on an orange gradient background with hexagonal graphics. Four Medik8 serums are shown. From left: C-Tetra dropper bottle (7% Vitamin C, for sensitive skins or beginners), C-Tetra Luxe dropper bottle (14% Vitamin C, for dry skin), C-Tetra Advanced pump bottle (20% Vitamin C, for normal, combination, and oily skin), and Super C Ferulic dropper bottle (30% Ethylated L-Ascorbic Acid, for experienced users).
A 30mL amber pump bottle of Medik8 C-Tetra Advanced standing next to its white cardboard carton against a clean white background. Text on the bottle and carton reads "20% Vitamin C Gel-Serum," "Brighten & Age Defence," and "with Phyto Exosomes."
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C-Tetra® Advanced

  • Brighten
  • |
  • Even
  • |
  • Defend
20% Vitamin C Gel-Serum With Phyto Exosomes

Defend against premature skin ageing and achieve accelerated visible skin brightening. 

With a next-generation combination of 20% vitamin C and cutting edge phyto exosomes that help shield and improve the skin's recovery from exposure to environmental stressors which can cause premature ageing.

Clinically proven to brighten skin and visibly improve wrinkles in 7 days[1] with 0% barrier disruption[1], C-Tetra Advanced is engineered for high-performance visible brightening, skin smoothing, and daily antioxidant defence. 

This intelligent ingredient complex combines potent, stabilised 20% vitamin C with restorative phyto exosomes and omni-antioxidant acetyl zingerone to neutralise the ageing effects of free radicals. 

The result? A high-performance, age-defying vitamin C serum that works smarter, not harsher.
Full Size (30ml)
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A silver pump tube of Medik8 Crystal Retinal 6 resting on a diagonal swatch of its peach-coloured cream against a clean white background. Text on the right features a silver wreath badge reading "WINNER OF 45+ GLOBAL AWARDS" and claims it is the "No.1 Retinal SERUM WORLDWIDE."
Crystal Retinal®
  • Renew
  • |
  • Firm
  • |
  • Smooth
 Award-winning Age-Defying Vitamin A Night Serum
Select a Strength
Key Benefits
Dramatic Skin Brightening

Clinically proven to visibly brighten skin and even tone in 7 days for a radiant, luminous complexion.[1]

Premature Skin Ageing Defence

Shields skin from damaging free radicals, pollution, and daily environmental stressors to help defend against premature skin ageing.

Lightweight Finish

The fast-absorbing gel-serum texture hydrates, smooths, and primes, leaving skin instantly refreshed and ready for the day ahead.

Enhanced Skin Barrier Support

Powerful phyto exosomes deliver replenishing bioactives to skin cells rapidly & effectively, ensuring 0% barrier disruption.[1]

Smooth & Even Complexion

Clinically proven to visibly improve skin smoothness and texture in 7 days, leaving a soft, polished finish.[1]

Proven Results
7 days to visibly brighter skin[1]
7 days to visibly reduced wrinkles[1]
0% barrier disruption[1]
7 days to visibly smoother skin texture[1]
90% reduction of pollution damage to the skin’s surface[2]
[1] Proven via independent clinical study conducted over 4 weeks on 32 participants. [2] Proven via in vitro protein carbonylation data against particulate matter pollution on the stratum corneum and epidermis. [3] Proven via in vitro protein carbonylation study using European standard reference environmental pollutants. | Please Note: Product packaging shown may be different to the product received due to regional variations.
How to Use

First-time use

If you're new to C-Tetra Eye, we recommend a patch test at least 24 hours before first use. Learn how to patch test here.


How To Use

Apply as part of your morning skincare routine. Massage 2-3 pumps across the face, neck and décolletage. Follow with moisturiser and always finish with sunscreen. 

Uses per bottle

80
Guide to Layering
Step 1: Cleanse
Medik8 Surface Radiance Cleanse tube displayed on a clean white background with a large, translucent gel texture smear. Text identifies it as a Resurfacing AHA/BHA Mangosteen Cleansing Gel in a 150mL size.
Morning
Surface Radiance Cleanse™
Select a Size
Step 2: Tone
Medik8 Press & Glow tonic bottle stands against a clean white background with translucent liquid droplets and a puddle, highlighting its watery texture. Text identifies the product as a 200mL
Morning
Press & Glow®
Select a Size
Step 3: Brighten
Medik8 C-Tetra Advanced bottle displayed on a clean white background with translucent serum droplets, highlighting its lightweight gel-serum texture.
Morning
C-Tetra® Advanced
Full Size (30ml)
Step 4: Protect
Advanced Day Ultimate Protect™
Morning
Advanced Day Ultimate Protect™
Full Size (50ml)
Key Ingredients
20% Stabilised Vitamin C (Tetrahexyldecyl Ascorbate)

A highly potent yet gentle form of vitamin C for dramatic skin brightening and powerful antioxidant protection against premature skin ageing.

Phyto Exosomes

Encapsulated by nature, our phyto exosomes intelligently deliver proteins, lipids, and messenger molecules to skin cells. Together, alongside our supercharged vitamin C, they help prevent & reduce premature skin ageing by supporting healthier-looking, more resilient skin.

Acetyl Zingerone (pronounced ‘a-sea-tul’)

A super-antioxidant that works synergistically with vitamin C, enhancing its efficacy while neutralising ageing free radicals and shielding skin from environmental stressors.

Hyaluronic Acid

Draws moisture into the skin to instantly plump and deeply hydrate for a soft, supple complexion.

Acetyl Zingerone (pronounced ‘a-sea-tul’)

A super-antioxidant that works synergistically with vitamin C, enhancing its efficacy while neutralising ageing free radicals and shielding skin from environmental stressors.

Hyaluronic Acid

Draws moisture into the skin to instantly plump and deeply hydrate for a soft, supple complexion.

N-Acetyl Glucosamine (NAG)

A barrier-supporting, gentle, skin-refiner that smooths the look of pores while helping to increase the skin’s own natural hyaluronic acid levels over time.

Full List of Ingredients
C-Tetra® Advanced
20% Vitamin C Gel-Serum With Phyto Exosomes

Aqua (Water), Tetrahexyldecyl Ascorbate, Isododecane, Propanediol, Acetyl Glucosamine, Squalane, Tocopherol, Acetyl Zingerone, Camellia Sinensis (Green Tea) Leaf Vesicles, Hydroxyacetophenone, Sodium Hyaluronate, Cellulose, Avena Sativa (Oat) Kernel Extract, Glycerin, Hydroxyethyl Acrylate/Sodium Acryloyldimethyl Taurate Copolymer, Citrus Grandis (Grapefruit) Peel Oil, Sucrose Stearate, Tetrasodium Glutamate Diacetate, Ethylhexylglycerin, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Xanthan Gum, Sodium Benzoate, Cellulose Gum, 1,2-Hexanediol, Polysorbate 60, Sorbitan Isostearate, Citric Acid, Phenoxyethanol, Citral, Linalool, Limonene

*Although we try our best to ensure this list of ingredients is accurate there may be product upgrades from time to time, or slight variants between different regions based on local laws, meaning the only definitive ingredient list is that which is printed on the product packaging.
  • Clinically proven
  • Artificial fragrance free
  • Dermatologically tested
  • Proven gentle formula
  • Certified by the vegan society
  • Non-comedogenic
  • Tested on all skin types & tones
Expert Recommended

"With this kind of Vitamin C percentage, you're going to get maximum brightness to the skin in just 7 days."

DR EWOMA UKELEGHE
Medical & Cosmetics Doctor & Medik8 Global Ambassador

"It’s rare to see such a powerful brightening treatment that also strengthens and supports skin health from within - this does both."

DR BIBI GHALAIE
Cosmetic Physician & Medik8 Global Ambassador

"C-Tetra Advanced combines the potent power of vitamin C with barrier-supporting phyto exosomes alongside superantioxidant acetyl zingerone, to protect against premature skin aging. C-Tetra Advanced is scientifically proven to shield against the environmental stressors that cause premature skin aging, reducing damage by up to 78%."[3]

DANIEL ISAACS
Chief Product Officer & Founding Partner Of Medik8
A circular headshot portrait of a man with light brown hair and green eyes, smiling neutrally. He is wearing a white lab coat with 'Medik8' embroidered on the pocket and a black button-up shirt. The background is white.

The Vitamin C Serum Range

A bottle of Medik8 C-Tetra Lipid Vitamin C Radiance Serum open with its dropper resting diagonally across the top. Set against a clean white background, the bottle is surrounded by three clear puddles of serum, showcasing its liquid texture.
Morning
C-Tetra®
Full Size (30ml) | £45
Strength

7% Stabilised Vitamin C

Texture

Lightweight oil

Skin Types

New to Vitamin C, Sensitive skin

Benefits
  • Brightens
  • Ultra gentle
Key Ingredients
  • 7% Tetrahexyldecyl Ascorbate
  • Vitamin E
Medik8 C-Tetra Luxe serum bottle shown open with its glass pipette resting against the rim, displayed on a white background with clear, translucent serum droplets. The image includes a "GET THE GLOSS BEAUTY AWARDS GOLD 2024" seal in the top left and a "DERMATOLOGIST RECOMMENDED" emblem with a magnifying glass icon in the top right.
Morning
C-Tetra® Luxe
Full Size (30ml) | £62
Strength

14% Stabilised Vitamin C

Texture

Rich oil

Skin Types

All skin types, First signs of ageing

Benefits
  • Brightens
  • Nourishes
  • Softens Look Of Wrinkles
Key Ingredients
  • 14% Tetrahexyldecyl Ascorbate
  • Squalane
  • Maracuja Oil
Medik8 C-Tetra Advanced bottle displayed on a clean white background with translucent serum droplets, highlighting its lightweight gel-serum texture.
Morning
C-Tetra® Advanced
Full Size (30ml) | £72
Strength

20% Stabilised Vitamin C

Texture

Lightweight Gel-Serum

Skin Types

All skin types, Visible signs of ageing

Benefits
  • Brightens
  • Defends Against Premature Skin Ageing
  • Smooths Skin Texture
  • Visibly  Improves Wrinkles
  • Advanced Pollution Protection
  • 0% Barrier Disruption
Key Ingredients
  • Phyto Exosomes 
  • 20% Tetrahexyldecyl Ascorbate
  • Acetyl Zingerone
Medik8 Super C Ferulic serum bottle shown open with its glass pipette resting against the rim, displayed on a clean white background with translucent serum droplets. The amber glass bottle features the Medik8 logo and is labeled "SUPER C FERULIC Potent Vitamin C Brightening Serum" in a 30mL size.
Morning
Super C Ferulic™
Full Size (30ml) | £69
Strength

30% Stabilised Vitamin C

Texture

Rich, oil like serum

Skin Types

Advanced signs of sun induced ageing

Benefits
  • Brightens
  • Intense Dark Spot Reduction
  • Visibly Reduces Wrinkles
Key Ingredients
  • 30% Ethylated L-Ascorbic Acid
  • Ferulic Acid
  • Vitamin E
  • Turmeric Root Extract

Complete Your Regime

Reviews

Frequently Asked Questions

What strength vitamin C is C-Tetra Advanced?
C-Tetra Advanced contains 20% stabilised vitamin C (tetrahexyldecyl ascorbate).
Can I use C-Tetra Advanced alongside Crystal Retinal (vitamin A)?
Absolutely. We recommend it as part of our pioneering CSA PhilosophyⓇ which champions vitamin C plus sunscreen by day, and vitamin A by night as the simple secret to glowing, youthful-looking skin.
Can I use C-Tetra Advanced if I am pregnant or breastfeeding?
As a cosmetics company, we are unable to provide product advice for medical conditions such as pregnancy or breastfeeding. We strongly recommend discussing the ingredients with your GP or midwife before use. As general guidance, this product does not contain any ingredients which we would recommend avoiding during pregnancy unless advised by your doctor.
Can I layer C-Tetra Advanced with Liquid Peptides Advanced MP in the morning?
Yes, you can. C-Tetra Advanced and Liquid Peptides Advanced MP are both emulsion-based serums however C-Tetra Advanced is slightly thicker in texture. We recommend applying serums in order of thinnest to thickest consistency. Therefore apply Liquid Peptides Advanced MP first and then apply C-Tetra Advanced.
Does C-Tetra Advanced contain fragrance/essential oils?

C-Tetra does not contain synthetic fragrance. It features a subtle, naturally derived citrus aroma from a very low concentration of essential oils, designed to leave the sensorial experience without compromising skin comfort.

Where do I layer C-Tetra Advanced in my routine?
C-Tetra Advanced should be applied in the morning, after cleansing and toning, but before moisturiser and sunscreen. If you are using multiple serums, we recommend applying them in order of thinnest to thickest in texture. Since C-Tetra Advanced is an emulsion, it should be layered on top of water and oil-based serums. This ensures your skin gets the full benefits of each product.
Can I use C-Tetra Advanced if I’ve never used vitamin C before?
Absolutely. Although C-Tetra Advanced contains a potent 20% vitamin C, it has been formulated using a very gentle form of vitamin C called THDA (Tetrahexyldecyl Ascorbate) that is suitable for all skin types, even if you’re new to vitamin C. Alongside this, it contains many gentle actives such as phyto exosomes, which offer soothing properties to support the skin barrier. C-Tetra Advanced is also proven to be gentle on all skin types in independent clinical and consumer testing. This means anyone can enjoy C-Tetra Advanced without fear of irritation.
I think there’s product left in my bottle that I can’t access with the pump. What do I do?
As C-Tetra Advanced is a lightweight emulsion, it is a little thicker than water-based serums and therefore may flow more slowly, however, it was designed for use with a pump so it should still dispense with ease. If there is any residue that the pump is not dispensing, you can unscrew the pump and turn the bottle upside down to pour out any remaining product. This should not be required unless you have used up nearly all of the product.
Where do I layer C-Tetra Advanced in my routine?
C-Tetra Advanced should be applied in the morning, after cleansing and toning, but before moisturiser and sunscreen. If you are using multiple serums, we recommend applying them in order of thinnest to thickest in texture. Since C-Tetra Advanced is an emulsion, it should be layered on top of water and oil-based serums. This ensures your skin gets the full benefits of each product.
C-Tetra® Advanced
Full Size (30ml)
Full Size (30ml)