Oxidative Stress. What Is It And How Does It Affect Us?

Vitamin C is one of the most loved and used ingredients in millions of women’s daily skincare routines. But what is it? When do we use it? How do we choose the right cream/serum for our needs?

Vitamin C or ascorbic acid has the following proven benefits:

  1. Reduces the activity of matrix metalloproteinases (in short, MMPs – a group of enzymes with an essential role in skin aging and more). Vitamin C stops the destruction of collagen, and thus you will enjoy a skin full of elasticity for a longer time.
  2. Stimulates the production of type I and III collagen. After 30’s we all need an extra boost of collagen! So, thanks, Vit. C!
  3. Reduces melanin production. This is why it is so loved and used in combating hyperpigmentation and restoring the skin’s natural glow.

How do we choose the right vitamin C cream?

Vitamin C is a compound that needs stabilization. Thus, to be efficient and not oxidize, it must be kept in a place protected from the sun, in containers as dark as possible, and preferably made of glass.

The purest form of vitamin C is ascorbic acid, potent at concentrations between 10 – 20%. There is no scientific evidence to show a higher efficacy of vitamin C above this concentration.

15% ascorbic acid is the optimal concentration, and if you add vitamin E and ferulic acid to the game, you get what I like to call the killer combination! There are products on the market that contain these two BFF’s of vitamin C that increases its effectiveness and make it indispensable in your skincare routine.

 Can I use vitamin C if I have sensitive skin?

Careful! Ascorbic acid can be irritating, and you have to use it with caution in case of hypersensitive skin.

For those with very sensitive skin, but who do not want to give up the many vitamin C benefits, a suitable option is a tetrahexyldecyl ascorbate (THDA) derivative. I know Deciem has this type of serum.

When do we use it?

You can use it at any time, both in the morning and evening. If you are using retinol in the evening, then vitamin C must be applied in the morning. Don’t forget about sunscreen… minimum SPF 50. Every day regardless of the weather!

Possible enemies of vitamin C?

We need to pay more attention when using Vit C together with:

  • niacinamide: can rarely give flushes, those sensations of heat and redness that appear on the cheeks and give headaches. So, I recommend that niacinamide administration is at a distance of 12 hours of vitamin C.
  • Alpha hydroxy acids (AHA): do not destabilize vitamin C but can make it more irritating.
  • Retinoids: far too sensitive used together. Preferred variant: retinol in the evening and vitamin C in the morning.


We do not use vitamin C together with:

  • benzoyl peroxide
  • cleansing oils

Why? Because both benzoyl peroxide and cleansing oils can inactivate vitamin C and therefore all its benefits are lost.

I hope you found this article useful, and now you will use vitamin C as a real skincare PRO!

Tips: If you want to test the effectiveness of your vitamin C product, I suggest you cut an apple in half and put one or more of your favorite vitamin C serums or creams on one half. Leave both halves on the table and forget about them for a few hours. Towards the evening, go and check them. You will notice that the half with Vit C  is just as fresh or with minimal changes, unlike the other half, on which you did not use anything and has oxidized all this time.

 In this way works our skin too. Free radicals and pollutants from the environment are continually attacking us. Good thing, we have solutions!

With love,
Your dermatologist