Antioxidant Stability
Antioxidant Stability — how well an antioxidant ingredient resists degradation from exposure to light, air, heat, or water over the life of a product. Because many antioxidants oxidize easily, stability determines whether the active remains effective from manufacture through the end of use.
Key points
- Vitamin C in its pure L-ascorbic acid form is notably prone to oxidation and color change over time.
- Formulators improve stability with low pH, airless or opaque packaging, and pairings like vitamin E and ferulic acid.
- Visible darkening or a shift in smell can signal that an antioxidant has begun to degrade.
- Derivatives of some antioxidants are used to trade a degree of potency for greater shelf stability.
Frequently asked
How do I keep an antioxidant serum effective longer?
Store it away from heat and direct light and keep it tightly closed, since air and warmth accelerate oxidation of many antioxidant ingredients.
Does a browning vitamin C serum still work?
Mild color change may reflect early oxidation with reduced potency, and a deeply discolored product has likely lost much of its antioxidant activity.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
