The C-Tetra Range

Experience powerful antioxidant protection with our C-Tetra range, crafted to brighten skin and defend from daily environmental stressors. Featuring stabilised tetrahexyldecyl ascorbate serums and creams, these vitamin C formulas promote a visibly radiant, even-toned complexion while supporting long-term skin health. With progressive strengths of serums available, the range is designed to suit different skin concerns and experience levels, whether you're starting out or looking for advanced results. This will help you build a routine that reveals visibly smoother, more luminous and youthful-looking skin.
7 Products
C-Tetra®

C-Tetra®

Lipid vitamin C serum - Visibly brightens skin tone and minimises the signs of ageing

30ml / £45

C-Tetra® Luxe

C-Tetra® Luxe

Enhanced vitamin C radiance serum - Visible anti-ageing and brightening results

30ml / £60

C-Tetra Try Me With Carton Grey Background-3

C-Tetra® (Travel Size)

Lipid Vitamin C Radiance Serum

8ml / £15

C-Tetra Luxe Try Me - With Carton - Grey Background-4

C-Tetra® Luxe (Travel Size)

Lipid Vitamin C Enhanced Radiance Serum

8ml / £20

C-Tetra® Advanced-5

C-Tetra® Advanced

20% Vitamin C Gel-Serum With Phyto Exosomes

30ml / £70

C-Tetra® Eye-6

C-Tetra® Eye

Lipid Vitamin C Radiance Serum

7ml / £25

C-Tetra® Cream

C-Tetra® Cream

Lipid vitamin C cream - Hydrates and restores radiance, with powerful antioxidant protection

50ml / £55

Frequently Asked Questions

What is C-Tetra?

Medik8’s C-Tetra range features lightweight vitamin C formulas powered by tetrahexyldecyl ascorbate, a low-irritation derivative of vitamin C. They deliver exceptional antioxidant protection against harmful free radical damage while supporting collagen production for a visibly even, more youthful-looking complexion. 

Our products help to visibly brighten uneven tone, soften the look of fine lines and wrinkles, and defend skin against environmental stressors, all while remaining kind to sensitive skin.

The C-Tetra serums come in a choice of strengths: from the original 7% C-Tetra, to the nourishing 14% C-Tetra Luxe, and the powerful 20% C-Tetra Advanced, so you can select the level best suited to your skin.

Is tetrahexyldecyl ascorbate a good form of vitamin C?

Tetrahexyldecyl ascorbate (often shortened to THD ascorbate) is considered one of the most effective and gentle forms of vitamin C. Its oil-soluble nature allows it to penetrate the skin efficiently, while its stability means it remains potent for longer. 

Unlike some forms of vitamin C that can be irritating, THD is well-tolerated, making it suitable for even sensitive skin types, while still delivering the radiance-boosting and collagen-supporting benefits vitamin C is known for.

Do vitamin C serums really work?

Yes, vitamin C is one of the most extensively studied ingredients in skincare, celebrated for its antioxidant, radiance-boosting and age-defying power. It helps defend against premature ageing by neutralising free radicals and shielding skin from pollution and everyday environmental stressors.

Medik8's C-Tetra range combines supercharged vitamin C with squalane, vitamin E, and phyto-exosomes across all products. They are designed to brighten while offering distinct benefits. C-Tetra provides gentle brightening for sensitive skin, C-Tetra Luxe delivers nourishing hydration alongside radiance, and C-Tetra Advanced offers advanced age defence. The result is healthier, more resilient skin with a brighter, youthful-looking glow tailored to your specific needs.

What ingredients work well with tetrahexyldecyl ascorbate?

Tetrahexyldecyl ascorbate pairs well with a number of other ingredients. Daily SPF is its perfect partner, helping to protect skin against UV damage. Hydrating actives like hyaluronic acid or glycerin enhance its plumping effect, while niacinamide can further support skin barrier strength and refine texture.

How long does it take for C-Tetra to work?

Many people begin to see a fresher, more radiant glow within just a few weeks of daily use. For even faster results, Medik8's C-Tetra Advanced is a next-generation vitamin C gel-serum clinically proven to brighten skin and visibly reduce wrinkles in just 7 days.[1]

[1] Proven via independent clinical study conducted over 4 weeks on 32 participants.