Ascorbic Acid
Ascorbic acid, also known as Vitamin C or L-ascorbic acid, is the primary water-soluble antioxidant found in skin tissue. It is used in skincare concentrations typically between 5–20% and requires a pH below 3.5 in water-based formulations to remain stable and penetrate the skin effectively. It is extremely unstable and oxidizes easily in the presence of light or air, making formulation and packaging critical to its efficacy.
Ascorbic acid boosts the skin's own collagen production, helping to reduce wrinkles and improve skin firmness, as demonstrated in multiple peer-reviewed studies. It inhibits the enzyme tyrosinase to fade hyperpigmentation and brown spots. When used under sunscreen, it enhances UV protection, an effect further amplified when combined with Vitamin E and ferulic acid.
High concentrations (above 10%) may cause irritation or tingling, particularly for sensitive or rosacea-prone skin. The ingredient is extremely unstable and oxidizes rapidly when exposed to light or air; water-based formulas must be kept below pH 3.5 to remain effective. Airless packaging is strongly recommended, and opened products should typically be used within three months.
