Ascorbic Acid

What is it?

Ascorbic acid (L-ascorbic acid), the active form of vitamin C, is a water-soluble antioxidant widely used in skincare for its roles in collagen synthesis and photoprotection, though it is notoriously unstable and requires careful formulation to remain effective.

What does it do?

A double-blind, placebo-controlled clinical trial found that a 5% topical vitamin C cream applied daily for 6 months produced a significant clinical improvement in photoaged skin, including increased skin microrelief density, reduced furrow depth, and ultrastructural evidence of elastic tissue repair.

Who may benefit?

• May help with: Dullness
• May help with: Hyperpigmentation & Dark Marks

How to use

Typically formulated at around 5% in the clinically studied formulation, though commercial products vary more broadly.

Ingredients it works with

• Niacinamide — Compatible

  A long-standing skincare myth held that vitamin C and niacinamide react to cause flushing. That conclusion came from a 1960s study mixing the two under extreme heat, not normal skincare conditions — at cosmetic concentrations and modern formulation pH, the two are considered compatible.

  Can be layered or used together; if a specific product visibly changes colour or texture on mixing, that formulation may be unstable and is worth flagging separately.

Use with caution

• Retinol — Space out use

  L-ascorbic acid performs best at a low pH that can add irritation when layered directly with a retinoid.

  A common approach is vitamin C in the AM and retinoid in the PM.

Real products containing this

• Ascorbic Acid + Alpha Arbutin — The Ordinary

Sources