Vitamin C (ascorbic acid) is one of the most extensively studied skincare ingredients in existence. Despite the proliferation of trendy new actives, Vitamin C remains a cornerstone of evidence-based skincare. Here's why Dr Lindsay recommends it to almost every patient.

What Does Vitamin C Do for Your Skin?

Vitamin C is a powerful antioxidant with multiple benefits:

  • Brightens skin — Inhibits melanin production, reducing pigmentation and giving skin a more even, luminous tone
  • Boosts collagen synthesis — Vitamin C is essential for the production of collagen; topical application directly stimulates fibroblasts to produce more
  • Protects against UV damage — As an antioxidant, it neutralises free radicals generated by UV exposure (note: it complements but does not replace SPF)
  • Reduces fine lines — Via its collagen-stimulating effects
  • Fades post-inflammatory hyperpigmentation — Useful for acne marks and sun spots

What Concentration Should You Use?

The evidence supports concentrations between 10–20% L-ascorbic acid for optimum effect. Below 8%, the benefit is minimal. Above 20%, irritation increases without proportional gain. Most patients do well starting at 10% and working up to 15–20% as tolerance develops.

When Should You Apply It?

Vitamin C is best applied in the morning — its antioxidant properties work synergistically with your SPF to protect against UV damage throughout the day. Apply it to clean, dry skin before moisturiser and SPF.

What About Stability?

L-ascorbic acid (the most active form) is notoriously unstable and oxidises on exposure to light and air. A good Vitamin C serum should come in dark or opaque packaging. If your serum has turned orange or brown, it has oxidised and its efficacy is significantly reduced.

Alternatives to Consider

If you find pure Vitamin C irritating, more stable derivatives such as ascorbyl glucoside or sodium ascorbyl phosphate offer a gentler option, though they're slightly less potent.