The 30% in this serum is THD ascorbate, a vitamin C derivative — not 30% L-ascorbic acid. These are not comparable numbers, and a 30% derivative is not "stronger" than a 20% L-ascorbic acid serum. The active is oil-soluble and works at normal pH, so it does not sting.
For melasma-prone and reactive skin, that non-irritating quality is a genuine clinical advantage, because irritation can itself worsen pigmentation. THD is also very stable — no browning, no oxidation clock — and the antioxidant support here (CoQ10, vitamin E, ergothioneine) is unusually broad, in an airless pump.
The evidence for THD is thinner than for L-ascorbic acid at any concentration, and the clinical support is in-house. The formula is genuinely well built; the price is the sticking point.
| Key active | THD ascorbate 30% |
| Texture | Lightweight, non-greasy serum |
| Best for | Sensitive or melasma-prone skin that cannot use pure vitamin C |
| Approximate price | $155–$164 |
| Fragrance | Fragrance free |
The formula is genuinely well built, and the case for it is tolerability rather than potency.
THD ascorbate is oil-soluble and works at normal pH, so it does not sting. For melasma-prone and reactive skin — where irritation can actually worsen pigmentation — a non-irritating vitamin C is a real clinical advantage, not a marketing one.
It is very stable. No browning, no oxidation clock.
The antioxidant support is unusually broad — CoQ10, vitamin E, ergothioneine — and the airless pump is the right packaging.
"30%" is not what most readers will think it is. It is 30% of THD ascorbate, a derivative — not 30% L-ascorbic acid. These are not comparable numbers, and a 30% derivative is not "stronger" than a 20% L-ascorbic acid serum. The marketing leans on a number that invites exactly that mistake.
$164 is a lot for a derivative. The Ordinary sells 20% THD ascorbate for around $20. You are getting a more sophisticated formula — you are not getting eight times the vitamin C.
The evidence for THD is thinner than for L-ascorbic acid, at any concentration.
The clinical support is in-house, not independent.
Water (Aqua), Tetrahexyldecyl Ascorbate, Pentylene Glycol, Hydrolyzed Eruca Sativa Leaf, Glycerin, Zea Mays (Corn) Starch, Cetearyl Glucoside, Hydrogenated Lecithin, Acetyl Zingerone, Palmitoyl Glycine, Cyclopentasiloxane, Glyceryl Caprylate, Plantago Lanceolata Leaf Extract, Diglucosyl Gallic Acid, Squalane, Sodium Carboxymethyl Beta-Glucan, Euterpe Oleracea Fruit Extract, Ergothioneine, Punica Granatum Extract, Tocopherol, Ubiquinone, Acrylates/C10-30 Alkyl Acrylate Crosspolymer, Triethanolamine, Tocopheryl Acetate, Leuconostoc/Radish Root Ferment Filtrate, Phenoxyethanol, Disodium EDTA, PPG-12/Smdi Copolymer, Xanthan Gum
1. Hydroquinone-Free, Tetrahexyldecyl Ascorbate Antioxidant Serum for Hyperpigmented and Photodamaged Skin to Achieve Skin Health (https://pmc.ncbi.nlm.nih.gov/articles/PMC13058394/) — A 30% THD ascorbate serum reduced blue-light ROS by 82-88% and cut melanin production in tissue models, supporting the claims that THD ascorbate is a stable, broadly antioxidant vitamin C with real pigmentation benefit for hyperpigmented skin. 2. Topical Vitamin C and the Skin: Mechanisms of Action and Clinical Applications (https://pmc.ncbi.nlm.nih.gov/articles/PMC5605218/) — Confirms L-ascorbic acid needs a pH below 3.5 for stability and penetration (contrasting with THD ascorbate working at normal pH without stinging) and that vitamin C inhibits tyrosinase and reduces melanin, supporting the melasma/pigmentation rationale. 3. Tetrahexyldecyl Ascorbate (Explained + Products) (https://incidecoder.com/ingredients/tetrahexyldecyl-ascorbate) — Confirms THD ascorbate is an oil-soluble, stable ester derivative of vitamin C that must be converted to pure vitamin C in skin, supporting the claim that '30%' is 30% of a derivative and not 30% L-ascorbic acid. 4. C+ Correcting Complex 30% - Vitamin C | Revision Skincare (https://revisionskincare.com/products/c-correcting-complex-30) — Manufacturer page confirms the product contains 30% THD ascorbate plus antioxidants ubiquinone (CoQ10), tocopherol (vitamin E) and ergothioneine, dispensed via a pump.