Vitamin C

What is vitamin C?

Vitamin C occurs naturally in the skin, but it is quickly used up by UV radiation, pollution and stress. The body cannot produce it itself. In skincare it is therefore applied directly – either as pure ascorbic acid (L-ascorbic acid) or as a more stable derivative, for example:

• Ascorbyl glucoside and sodium ascorbyl phosphate – mild and stable, ideal for sensitive skin
• Ethyl ascorbic acid – stable and effective
• Ascorbyl tetraisopalmitate – oil-soluble, often found in creams and oils

Pure ascorbic acid is the most potent, but it is sensitive to light, air and heat and can irritate sensitive skin.

How does vitamin C work on the skin?

• Antioxidant protection: Vitamin C neutralises free radicals that are formed by UV radiation and environmental stress and accelerate skin ageing.
• Dark spots: It slows down melanin production and fades sun spots and post-acne marks.
• Collagen production: The skin needs vitamin C to build its own collagen.
• Glow: The complexion looks fresher, brighter and more even.

Which skin types is vitamin C suitable for?

• dull, tired skin – see Glow skincare
• skin with dark spots and post-acne marks – see Dark spots
• mature skin with first wrinkles
• sensitive skin – best to start with mild vitamin C derivatives

How to use vitamin C

Vitamin C works best as protection during the day:

1. In the morning, cleanse your face and apply a toner.
2. Apply the vitamin C serum to dry skin.
3. Finish with a cream and always with sunscreen – vitamin C and sun protection boost each other.

Store vitamin C serums in a dark place and tightly closed. If a serum turns noticeably orange or brown, it has lost its effectiveness.

What can you combine vitamin C with?

• Hyaluronic acid for hydration
• Vitamin E and ferulic acid – stabilise vitamin C and enhance its protective effect
• Niacinamide – modern formulas work well together; if you notice redness, use them at different times of day
• Ceramides and panthenol for sensitive skin

Take care when using pure ascorbic acid at the same time as retinol, strong AHA or BHA peels and copper peptides. The simple solution: vitamin C in the morning, retinol and acids in the evening.

Vitamin C in Korean skincare

In K-beauty, vitamin C often comes in mild, stable forms – in serums, toners, toner pads and capsule creams. Combinations with glutathione, niacinamide or tranexamic acid for a bright, even complexion are popular, for example in medicube’s Deep Vita C line or Goodal’s Green Tangerine products. Our Korean vitamin C skincare collection has more than 150 products.

What does the research say?

Vitamin C is one of the best-studied antioxidants. Studies show that pure ascorbic acid penetrates the skin best at a low pH below 3.5 and at concentrations between 10 and 20% (Pinnell et al., Dermatologic Surgery, 2001). Combining it with vitamin E and ferulic acid improves stability and protection (Lin et al., Journal of Investigative Dermatology, 2005). Milder derivatives work more slowly but are often the better choice for sensitive skin.