Board-Certified Plastic Surgeon
Your skin is changing.
A plastic surgeon built this for exactly this moment.
I operate on skin every day. I see what happens at the cellular level. The Anti-Oxidant Vitamin Serum is the same standard I bring to the operating room — formulated for skin that deserves precision, not guesswork.
-dr. koo
20% OFF YOUR FIRST ORDER WITH CODE WELCOME20
Begin Your Protocol★★★★★ 4.9 Average · 90+ Patient Reviews From Dr. Koo's Practice · Post-Procedure Recommended · Surgeon-Formulated
The Surgeon's Story
I built this for surgical patients. Then I asked: why should the best skin science be limited to the operating room?
After more than three decades in plastic surgery, I watched my patients heal beautifully with clinical-grade formulations. But outside the clinic, they were left with products that promised everything and delivered very little. I knew the science existed to do better. So I formulated what I would actually prescribe — and made it available to every woman who believes her skin deserves the same precision I bring to the operating room.
I know what tissue needs to heal — because healing is my life's work.
-dr. koo
The Science
Why THD-Ascorbate
Most serums use conventional water-soluble Vitamin C that cannot penetrate your skin's lipid barrier. It oxidizes on contact with air, stings on application, and never reaches the cells that actually produce collagen.
I chose THD-Ascorbate (Tetrahexyldecyl Ascorbate) because it is lipid-soluble — it crosses the stratum corneum and is activated intracellularly by esterases inside the fibroblast, where your body actually makes collagen. It serves as the cofactor for prolyl hydroxylase, the enzyme responsible for stabilizing collagen's triple-helix structure.
3x
Deeper Penetration
50x
Greater Bioavailability
15%
THD-Ascorbate, Stated Outright
Formulated with THD-Ascorbate + Vitamins D, E, F, K + Ceramides + Jojoba Esters. Neutral pH. Non-acidic. Stable to the last drop.
The Pairing
Why the Serum Comes First
Retinol signals the fibroblast to build collagen. Ascorbate is the cofactor the fibroblast needs to finish it. This serum goes on first; the retinol layers on top.
Our Retinol, Independently Measured
13.4%
improvement in fine lines and wrinkles at 8 weeks, measured by Visia imaging — 100% of participants improved
16.1%
improvement in elasticity at 8 weeks, measured by Cutometer — 94% improved
0
cases of irritation in 33 women, at any visit
Independent 8-week clinical study, Essex Testing Clinic · pH Optimum Retinol Level 3 · 33 women, ages 46–69 · nightly use
What the Serum Adds
It finishes the collagen. Ascorbate is the required cofactor for prolyl hydroxylase, the enzyme that lets new procollagen fold into a stable triple helix. Without it, what retinol asks for is never completed.
It protects the result. THD-Ascorbate converts to active ascorbic acid inside skin and defends it against UV-driven oxidative damage — the collagenase trigger that undoes the work.2
The pair is studied. A published histological study of a topical retinol–vitamin C combination found it partially reversed changes of both chronological aging and photoaging in treated skin.1
1 Seité S, et al. Skin Pharmacol Physiol. 2005;18(2):81–87. 2 Ochiai Y, et al. J Dermatol Sci. 2006;44(1):37–44.
Your Protocol
One Serum. Two Protocols. 24-Hour Architecture.
Your skin doesn't stop working at night. Neither should your Vitamin C.
AM — Shield
Protect
Apply THD-Ascorbate Serum to clean skin. Follow with your sunscreen. THD-Ascorbate neutralizes the UV damage that gets through your SPF — stable and active all day because it is lipid-soluble.
ANTIOXIDANT SHIELD + UV DEFENSE
PM — Rebuild
Repair
Apply THD-Ascorbate Serum, then layer your retinol. Unlike conventional water-soluble Vitamin C, THD-Ascorbate has a neutral pH that works alongside retinol without destabilizing it. Retinol tells your skin to make more collagen. THD-Ascorbate ensures that collagen holds its structure.
COLLAGEN ACTIVATION + STRUCTURAL REPAIR
Your Welcome Offer
Anti-Oxidant Vitamin Serum
★★★★★ 4.9 average · 90+ patient reviews from Dr. Koo's practice
THD-Ascorbate + Vitamins D, E, F, K + Ceramides + Jojoba Esters
Surgeon-formulated. Post-procedure recommended. Neutral pH.
Less than $3.50 per day for surgeon-formulated skin science.
Add to ProtocolMost prestige vitamin C serums use L-ascorbic acid: water-soluble, quick to oxidize, and held at a low pH that does not layer with retinol. THD-Ascorbate is lipid-soluble, stable to the last drop, and works in both your AM and PM protocols.
Direct Access to Dr. Koo
Real questions answered by a real surgeon. Not a chatbot.
Complimentary Shipping
Complimentary shipping on every order. No minimums.
60-Day Guarantee
If you are not satisfied, full refund. No questions, no hassle.
Post-Procedure Recommended
The serum I recommend to my own surgical patients as skin heals.
★★★★★
“I have spent thousands on skincare over the years. This is the first time I have looked in the mirror and actually seen a difference. My skin has a clarity and firmness I thought was gone forever. I only wish I had found Dr. Koo sooner.”
Patient of Dr. Koo · Age 62 · Shared with permission
Your Next Step
Your Protocol Starts Here
This is the protocol I give my own patients: THD-Ascorbate under sunscreen by day, THD-Ascorbate with retinol by night. The same standard I bring to the operating room goes into every bottle.
-dr. koo
Use code WELCOME20 at checkout. Have questions first? Reply to any email from us — Dr. Koo reads every message.