Vitamin C (L-Ascorbic Acid)
What it is
Vitamin C, in its most bioactive form L-ascorbic acid, is a potent water-soluble antioxidant essential for cutaneous health. It functions as a cofactor for prolyl and lysyl hydroxylases, enzymes critical for collagen biosynthesis, while simultaneously neutralising reactive oxygen species generated by UV exposure and environmental pollutants. Various stable derivatives exist (ascorbyl glucoside, ascorbyl tetraisopalmitate, sodium ascorbyl phosphate), each with distinct penetration profiles and stability characteristics.
What it helps with
- Neutralising free radicals and providing photoprotection when combined with SPF
- Inhibiting tyrosinase activity to reduce melanin synthesis
- Stimulating fibroblast proliferation and collagen production
- Brightening overall complexion and reducing sallowness
- Accelerating wound healing through enhanced collagen deposition
- Reducing the appearance of fine lines associated with photoageing
Common concerns it addresses
Best for
Clinical suitability
- Indicated for patients seeking photoprotection enhancement
- Appropriate for early intervention in chronological and photoageing
- Beneficial for post-inflammatory hyperpigmentation management
- Suitable as adjunctive therapy following laser resurfacing (once re-epithelialisation is complete)
- Safe during pregnancy and lactation
Use with caution
- Sensitive or reactive skin types may experience stinging with L-ascorbic acid
- Those using high-strength retinoids may find layering challenging — consider alternate timing
- Patients prone to contact dermatitis should patch test new formulations
- Low-pH formulations may exacerbate active inflammatory conditions
Not ideal for
- Highly sensitised or compromised skin barriers (stabilise barrier first)
- Immediately post-procedure before full re-epithelialisation
- Those who cannot tolerate low-pH formulations
- Patients with G6PD deficiency (theoretical concern with high-dose topical application)
How it's commonly used
L-ascorbic acid formulations require pH levels between 2.5-3.5 for optimal penetration and are typically used at concentrations of 10-20%. Apply in the morning to cleansed, dry skin before SPF application. Store in dark, airtight packaging as L-ascorbic acid oxidises rapidly. Discard if the solution turns brown or develops an unusual odour. Stable derivatives may be preferable for those with sensitive skin or in humid climates.
Pairs well with
Clinic note
We frequently prescribe vitamin C as the cornerstone of a preventative anti-ageing protocol. For patients presenting with melasma or significant photodamage, we typically combine topical vitamin C with other tyrosinase inhibitors for enhanced efficacy. Those with reactive skin often tolerate derivatives such as ascorbyl glucoside better than L-ascorbic acid. Formulation quality is paramount — poorly stabilised products offer minimal clinical benefit.
Ingredient-focused product examples
Clinically curated examples featuring this ingredient. These are optional references to help guide your product research.
Brightening Vitamin C Serum
Potent antioxidant serum formulated to protect against environmental damage and enhance skin radiance.
View productDaily Radiance Booster
Lightweight formula that helps fade dark spots and improve overall skin luminosity over time.
View productThis content is provided for educational purposes and does not replace personalised medical advice. Individuals with skin conditions, those who are pregnant, or those undergoing dermatological treatments should seek professional guidance before introducing new active ingredients.
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