Not all Vitamin C serums are created equal — and the TIRTIR Pure Vitamin C24 Serum is proof of what happens when you combine a genuinely high concentration with an exceptionally well-considered supporting formula. This serum delivers 24% pure Ascorbic Acid (L-Vitamin C) — one of the highest concentrations you'll find in a commercially available serum — stabilised in a propanediol base that maintains potency without oxidising quickly.

Ascorbic Acid at this level is a clinically proven brightener, collagen stimulator, and antioxidant. It visibly fades dark spots, post-acne marks, and hyperpigmentation, evens skin tone, and gives the skin the kind of lit-from-within radiance that's hard to achieve with lower-concentration formulas. What makes TIRTIR's version particularly clever is the decision to buffer the formula with not one, not two, but three forms of collagen (Soluble Collagen, Hydrolyzed Collagen, and Atelocollagen) to counteract the potential dryness and irritation that high-dose Vitamin C can cause.

Then there's the CICA-7 Complex — seven Centella Asiatica-derived actives including Madecassoside, Asiaticoside, Asiatic Acid, and Madecassic Acid — delivering serious soothing support alongside the Vitamin C. Alpha-Bisabolol (0.5%) blurs the appearance of post-inflammatory redness, and Acetyl Hexapeptide-8 rounds out the anti-ageing work.

This is the Vitamin C serum for people who've tried diluted versions and been underwhelmed. Sul Skin stocks it for anyone serious about brightening and anti-ageing — always follow with SPF in the morning.