C-Tetra Advanced

Vitamin C without the sting

Tetrahexyldecyl ascorbate, second in the formula, is the oil-soluble vitamin C ester: it slips into skin lipids intact, converts to active vitamin C within, and spares the surface the acidity that makes L-ascorbic serums tingle. The trade is gentleness and stability for raw speed.

The bodyguard pairing

Acetyl zingerone, the ginger-derived antioxidant, quenches radicals, absorbs part of the blue-light range and, its quiet speciality, chelates the metal ions that degrade vitamin C in the bottle and on the skin. The pairing extends the serum’s working life at both ends.

The hydration understorey

N-acetyl glucosamine, one of hyaluronic acid’s own two building blocks, supports the skin’s water-holding matrix from within, joined by sodium hyaluronate, squalane, oat and green tea delivered in lipid vesicles.

The scent note

Grapefruit peel oil provides the citrus lift, with citral, linalool and limonene declared, noted below.

Skin that wants daily vitamin C but finds L-ascorbic serums stingy or unstable, including sensitive skin, retinoid users needing a gentle morning half, and anyone starting the CSA routine Medik8 built its name on: vitamin C plus sunscreen by day, vitamin A by night.

Worth knowing

Contains grapefruit peel oil with three declared fragrance allergens, patch test with citrus or fragrance allergy. N-acetyl glucosamine is commonly shellfish-derived; reactions to the purified sugar are rare, but the severely shellfish-allergic may prefer to patch test first.

Mornings on clean, dry skin: 3–4 drops pressed over face and neck, followed by moisturiser and SPF. Its gentleness makes daily use from day one realistic, no ramp-up needed.

Store away from direct sun; the ester is stable but not immortal.

Use alongside

The middle rung of the C-Tetra ladder, C-Tetra is the entry point, Advanced adds the acetyl zingerone stabiliser and hydration bench, Luxe wraps the ester in oil for dry skin. One C serum per routine across the whole shelf: alongside Super Serum it is among the calmest, with Aox Ferulic, GeneXC and Extreme C 20 as the L-ascorbic temperaments. Pairs naturally with an evening retinoid as the morning half of the classic day-night split, under any moisturiser, always beneath SPF.