Medik8 C-Tetra Advanced™

All three serums use stabilised tetrahexyldecyl ascorbate (THDA) but at different strengths. C-Tetra contains 7% vitamin C and is ideal for beginners or sensitive skin. C-Tetra Luxe delivers 14% vitamin C in a richer, oil-serum texture with added squalane and red ginseng for extra nourishment. C-Tetra Advanced is the most potent at 20% vitamin C, formulated as a lightweight gel serum with phyto exosomes and acetyl zingerone for maximum brightening and antioxidant defence whilst remaining gentle on all skin types.

Despite containing a potent 20% vitamin C, C-Tetra Advanced has been formulated with THDA — an ultra-gentle form of vitamin C suitable for all skin types, including sensitive skin. The formula also contains phyto exosomes which offer soothing properties to support the skin barrier. Independent clinical and consumer testing has proven C-Tetra Advanced is gentle on all skin types with 0% barrier disruption, so anyone can enjoy this serum without fear of irritation.

Absolutely. Medik8 recommends using C-Tetra Advanced as part of their pioneering CSA Philosophy® — vitamin C plus sunscreen by day, and vitamin A by night. This combination is their proven pairing for more youthful-looking, glowing skin. Apply C-Tetra Advanced each morning and pair it with a retinal serum such as Crystal Retinal in the evening for optimal age-defying results.

Yes. C-Tetra Advanced is clinically proven to deliver visible improvements in skin tone and hyperpigmentation in just 7 days. The 20% stabilised vitamin C works to visibly brighten uneven skin tone and reduce the appearance of dark spots, whilst N-acetyl glucosamine helps to smooth the complexion and support a more even appearance over time.

C-Tetra Advanced is an emulsion-based serum, so it should be layered on top of water-based and oil-based serums. Apply serums in order of thinnest to thickest consistency. For example, if using Liquid Peptides Advanced MP, apply that first, then follow with C-Tetra Advanced. Always finish with moisturiser and sunscreen.

Both are high-strength vitamin C serums, so Medik8 recommends choosing just one in your regime. Super C Ferulic contains 30% ethylated ascorbic acid and is recommended for mature skin showing advanced signs of sun-induced ageing such as significant hyperpigmentation — but it is not suitable for sensitive skin and requires patch testing. C-Tetra Advanced contains 20% THDA in a creamy gel formula boosted by phyto exosomes and acetyl zingerone, making it the better choice if you have sensitive skin or prefer a gentler, barrier-supporting formula.

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 designed to offer an energising start to your morning skincare routine. If you are familiar with the original C-Tetra or C-Tetra Luxe serums, you can expect the same signature citrus scent.

As a cosmetics company, Medik8 is unable to provide product advice for medical conditions such as pregnancy or breastfeeding. They strongly recommend discussing the ingredients with your GP or midwife before use. As general guidance, this product does not contain any ingredients which Medik8 would recommend avoiding during pregnancy unless advised by your doctor.

Phyto exosomes are naturally encapsulated micro-carriers sourced from green tea leaves. They are rich in proteins, lipids and messenger molecules that act as intelligent delivery systems, carrying key signalling molecules like peptides and nutrients to skin cells. In C-Tetra Advanced, phyto exosomes help to soothe the skin, reinforce the barrier and support optimal skin tolerance and comfort alongside the potent 20% vitamin C.