to visibly brighter skin[1]
The C-Tetra Range
Discover the C-Tetra range – a powerhouse vitamin C range tailored to every skin need. Now joined by NEW C-Tetra Advanced, the collection features three expertly formulated serums with escalating strengths of stabilised tetrahexyldecyl ascorbate (THDA) which is our chosen vitamin C for these formulas: C-Tetra (7% vitamin C), C-Tetra Luxe (14% vitamin C), and C-Tetra Advanced (20% vitamin C).
Known for its radiance-boosting and collagen-supporting abilities, vitamin C helps visibly brighten uneven skin tone while protecting against environmental stressors. Whether you’re new to vitamin C or ready to level up, there’s a C-Tetra for you.
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C-Tetra Advanced
Meet C-Tetra Advanced: a next-generation, age-defying vitamin C gel-serum clinically proven to brighten and visibly reduce wrinkles in just 7 days.[1]
Powered by 20% stabilised vitamin C, phyto exosomes and acetyl zingerone, it defends against premature skin ageing - delivering high-performance results with 0% barrier disruption.[1]
This is vitamin C but not as you know it.
C-Tetra Advanced Claims
to visibly reduced wrinkles[1]
barrier disruption[1]
C-Tetra Advanced Results
C-Tetra Luxe Claims
to visibly brighter, more youthful-looking skin[2]
visible hyperpigmentation had reduced in just 4 weeks[2]
noticed smoother and softer skin after just 1 use[2]
C-Tetra Luxe
Experience elevated radiance with C-Tetra Luxe – a nourishing 14% vitamin C serum enriched with squalane, maracuja oil and red ginseng. It hydrates and brightens while supporting collagen for a smoother, more luminous complexion.
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C-Tetra Claims
to restored skin radiance[3]
agree skin feels instantly softer[3]
of sensitive skins agreed C-Tetra was gentle on the skin[3]
C-Tetra
C-Tetra is Medik8’s gentle yet powerful 7% vitamin C serum, ideal for sensitive skin or first-time users. Formulated with stabilised tetrahexyldecyl ascorbate and vitamin E, it visibly brightens, smooths fine lines, and boosts radiance in just 7 days[3] - delivering antioxidant protection for a more youthful and healthy-looking complexion overall.
Shop NowFAQs
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(R) 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 Advanced is free from artificial fragrances but does contain a natural, uplifting citrus fragrance derived from essential oils. The scent is refreshing and is designed to enhance your experience and offer an energising start to your morning skincare routine. If you are familiar with our C-Tetra and C-Tetra Luxe serums, you can expect to smell the same scent.
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.
[1] Proven via independent clinical study conducted over 4 weeks on 32 participants.
[2] Proven via independent clinical study on C-Tetra Luxe conducted over 4 weeks on 36 participants
[3] Proven via independent consumer study conducted over 4 weeks on 52 participants with sensitive skin.