Medik8 C-Tetra Advanced on a warm cream background
Medik8 C-Tetra Advanced
Medik8 C-Tetra Advanced

Antioxidant

Medik8 C-Tetra Advanced

A lightweight 20% THD ascorbate antioxidant emulsion for people who want a potent but wearable vitamin C step.

£69.00 £23.00/10ml
30ml
Best suited to
You want a high-strength vitamin C derivative in a light, slightly hydrating texture.
Another option may be better if
You prefer an oil-based serum or want a simpler, lower-cost antioxidant.

Earn 5% back in Curatory Credit

Our way of saying thank you as you build your skincare routine with The Curatory.

How Curatory Credit works

Why I chose it

Vitamin C can be difficult to formulate well. What I like about C-Tetra Advanced is that it combines a high concentration of THD ascorbate with a light gel-serum texture that is quick to apply and easy to layer under other skincare and make-up.

If your skin is feeling sensitive and you want a break from stronger actives, this and sunscreen give you a simple morning routine that supports a comfortable skin barrier.

Dr Max GreenfieldMBBS, BSc, MRCS(Eng)

Where this fits

A broad guide to where this sits, without assuming how many steps your routine has.

Morning
Comes afterCleansing and any toner or mist
This product Medik8 C-Tetra Advanced
Comes beforeOther leave-on products and SPF
Curate your full skincare routine
How to introduce it

Use once daily in the morning. After cleansing and any toner or mist, massage three pumps over the face and neck.

Allow it to absorb for a few moments before applying other leave-on products, moisturiser and sunscreen.

Guidance continues after purchase. We can help you introduce, simplify or adjust this product.

The ingredients that make this special

A closer look at the ingredients doing the most meaningful work in this formula—and what the evidence can reasonably tell us.

Tetrahexyldecyl Ascorbate

An oil-soluble form of vitamin C that provides antioxidant support.

Read the clinical context

Tetrahexyldecyl ascorbate is an oil-soluble form of vitamin C. It provides antioxidant support and over time may help improve the appearance of uneven tone. Although it has been less extensively studied than L-ascorbic acid, it still has a good evidence base and is more suitable for those with sensitive skin.

Hyaluronic Acid

A well-established humectant moisturiser that helps the skin hold onto water.

Read the clinical context

Hyaluronic acid is a well-established humectant moisturiser that draws water into the upper layers of the skin. It works best alongside emollient and occlusive ingredients, which help soften the skin and reduce moisture loss.

Phyto Exosomes

Plant-derived vesicles included to support healthier-looking skin.

Read the clinical context

Plant-derived extracellular vesicles are an emerging area in topical skincare. Laboratory and manufacturer-led research suggests they may influence how skin cells communicate, but strong independent clinical evidence in finished products is still limited. They’re a useful addition, although the established ingredients in the formula remain the main reason to choose it.

Acetyl Zingerone

A synthetic antioxidant inspired by compounds found in ginger.

Read the clinical context

Acetyl zingerone is an antioxidant inspired by compounds found in ginger. It helps protect the formula and skin from oxidative stress and may also help keep the vitamin C stable. How much difference it makes will depend on the concentration and the rest of the formula.

N-acetyl Glucosamine

An amino sugar that can help improve hydration and the appearance of uneven tone.

Read the clinical context

N-acetyl glucosamine is an amino sugar involved in the skin’s natural production of hyaluronic acid. Over time, it can help improve hydration and the appearance of uneven tone, particularly when paired with niacinamide.

View the complete ingredients list

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

More about Medik8

Medik8 develops and manufactures virtually all of its products at its ISO-certified innovation centre near London. Its in-house scientists focus on formulation, stability and ingredient delivery rather than following a trend simply because it is popular.

That work is visible across several of its best-known ranges: the progressive Crystal Retinal strength ladder; C-Tetra serums built around a stable form of vitamin C; its research into peptide combinations and delivery; and high-quality daily sunscreens designed to make reliable UVA and UVB protection easier to use consistently. The products do different jobs, but they share a useful principle: thoughtful formulation should help proven ingredients fit into real routines.