There is no widely agreed Korean copy of C E Ferulic’s formula. Several lists pretend there is.
SkinCeuticals C E Ferulic is a low-pH water serum of 15% L-ascorbic acid, 1% alpha-tocopherol, and 0.5% ferulic acid. Korean “vitamin C” is usually a more stable derivative. Some roundups even list products with no vitamin C at all.
What the original actually is
| Product | SkinCeuticals C E Ferulic |
|---|---|
| Formula | 15% L-ascorbic acid + 1% vitamin E (alpha-tocopherol) + 0.5% ferulic acid |
| pH window in the literature / patent talk | Roughly 2.0–3.5, often cited around 2.5–3.2 |
| US price we checked | $185 for 30 ml (Dermstore, August 2026) |
| Why people copy it | Published antioxidant work on this ratio; L-ascorbic acid is the form used in those papers |
L-ascorbic acid is pH-sensitive and oxidizes. That is why the original stings for some people and why it is packed the way it is. A 3-O-ethyl ascorbic acid or ascorbyl glucoside serum is a different molecule. It can still brighten. It is not this formula.
Not formula matches (even when labeled “dupes”)
Beauty of Joseon Glow Serum
INCI leads with propolis extract, then solvents, then niacinamide 2% per the brand. There is no L-ascorbic acid, no ferulic acid dose, no 15% vitamin C. It is a glow/soothing serum. Putting it on a C E Ferulic dupe list is a job-category error.
numbuzin No.5 Vitamin Concentrated Serum
Public brand copy and Korean retail writeups describe niacinamide, panthenol, tranexamic acid, and glutathione — a brightening blend. That is not 15% L-ascorbic acid. Useful for tone. Wrong column for “CE Ferulic dupe.”
innisfree Green Tea Enzyme Vitamin C Brightening Serum — job match
This one at least is vitamin C, but the current product listing uses derivative forms rather than L-ascorbic acid. The official US ingredient list includes 3-O-ethyl ascorbic acid and ascorbyl tetraisopalmitate. Same job family (morning antioxidant / brightening). Not the Duke trio.
Green Tea Enzyme Vitamin C Serum on innisfree C E Ferulic on SkinCeuticals
If you actually want the same formula
That lane is mostly not Korean. Names that publicly aim at 15% L-ascorbic acid with vitamin E and ferulic include Timeless, Paula’s Choice C15 Super Booster, Maelove Glow Maker, and e.l.f. SKIN Bright Icon. Concentrations, pH, and packaging still differ. We are not ranking them here; we are refusing to hide them behind a K-beauty label.
Side by side
| C E Ferulic | innisfree Vitamin C serum | Joseon Glow Serum | numbuzin No.5 | |
|---|---|---|---|---|
| Vitamin C form | 15% L-ascorbic acid | 3-O-ethyl ascorbic acid + ascorbyl tetraisopalmitate | None | Not the 15% L-AA trio |
| Other actives | 1% E + 0.5% ferulic | Green tea enzyme + vitamin C derivative system | Propolis + 2% niacinamide | Niacinamide, TXA, glutathione |
| On this site | Original | Job match | Not a match | Not a match |
What this page is not saying
Korean brightening serums can be good. They are mostly a different chemistry. If a page tells you numbuzin or Joseon Glow “is” C E Ferulic, it is selling a vibe.
Related antioxidant and brightening comparisons
These pages separate a vitamin C formula question from other ways of approaching uneven tone:
- SkinCeuticals Discoloration Defense vs Anua — TXA, kojic acid and niacinamide, not the L-ascorbic-acid trio.
- Caudalie Vinoperfect vs AXIS-Y — Viniferine positioning versus a 5% niacinamide serum.
Sources
- SkinCeuticals official C E Ferulic page: 15% L-ascorbic acid, 1% alpha-tocopherol, 0.5% ferulic acid, 30 ml and current US price, checked 26 August 2026. Dermstore listed the same product at $185 / 30 ml.
- US patent 7,179,841 describes the L-AA / tocopherol / ferulic / low-pH water system that the original is built on.
- Beauty of Joseon Glow Serum: brand page (propolis 60%, niacinamide 2%) and INKEEDecoder INCI.
- innisfree Green Tea Enzyme Vitamin C Brightening Serum: current product name and official US ingredient list, checked 26 August 2026.