Tetrahexyldecyl Ascorbate (THD Ascorbate) is a highly stable, oil-soluble Vitamin C ester. Unlike L-Ascorbic Acid, it penetrates both lipid and aqueous layers of skin and converts to active Vitamin C intracellularly. It provides antioxidant protection, collagen stimulation, and brightening with minimal irritation.
Key Skin Benefits
+ Oil-soluble — penetrates skin better than L-AA
+ Highly stable (no oxidation issues)
+ Stimulates collagen synthesis
+ Brightens hyperpigmentation and evens skin tone
+ Non-irritating at effective concentrations
Pros
+ No oxidation/instability problems of L-Ascorbic Acid
+ Works at lower concentrations (2-5%)
+ Penetrates both lipid and aqueous skin layers
+ Non-acidic, no stinging or irritation
+ Stable from pH 3-7
Cons
− Higher cost than L-Ascorbic Acid
− Less direct research than L-AA (fewer clinical studies)
− Conversion rate to active form is not 100%
− Oil-soluble — may not suit ultra-light water serums
Specifications
Property
Value
Usage Areas
Face, Eye, Body
Product Type
Leave-On
Source
Synthetic
Natural Level
Synthetic
Safety Ratings
Metric
Rating
Skin Sensitivity
0/5 (none to very low)
Comedogenic Rating
0/5
EWG Score
1/10
Regional Regulatory Limits
Region
Leave-on %
Rinse-off %
Status
EU (CosIng)
No limit
No limit
Allowed
US (CIR/FDA)
No limit
No limit
Allowed
Japan (MHLW)
No limit
No limit
Allowed
ASEAN
No limit
No limit
Allowed
China (NMPA)
No limit
No limit
Allowed
Typical Usage % by Product Type
Product Type
Typical %
Vitamin C serum
2 - 7%
Anti-aging moisturizer
1 - 3%
Eye cream
0.5 - 2%
References
Fitzpatrick RE & Rostan EF (2002) — Topical Vitamin C review. PMID: 11896774
Pinnell SR et al. (2001) — Topical L-Ascorbic Acid. PMID: 11293425