Is 20% vitamin C better than 10%?

Should you choose 10% or 20%?

If 10% already fits your routine without irritation, there is no need to increase the percentage simply because 20% exists. Sensitive skin calls for a low starting concentration. Dryness, itching and redness are possible side effects, so developing those symptoms is a reason to reconsider the product, not move up in strength.1

What matters besides the percentage?

Vitamin C needs to remain stable and reach the skin to be useful. L ascorbic acid is highly unstable when exposed to oxygen, and some preparations do not penetrate sufficiently to make a difference. A larger percentage on the carton is not a complete product assessment, even if it is the easiest part to print in enormous type.2

The base carrying vitamin C affects delivery because the skin's outer barrier blocks many substances. These percentage comparisons concern L ascorbic acid; a different vitamin C form is not a directly interchangeable strength. Choosing a serum means checking more than the front label, which would prefer to handle the entire interview.34

A tested formulation containing 20% vitamin C, 5% vitamin E, hexylresorcinol and silymarin improved brightness and uneven tone over 12 weeks. Its base contained no water, which helped reduce vitamin degradation. Think of 20% as one component of a complete formula, rather than a result you can buy independently of the other ingredients.4

How should you use vitamin C?

1. 1Cleanse your face, then apply toner if you use one.
2. 2Apply vitamin C serum after cleansing and toner. Morning use pairs it with sunscreen, although overnight use is also an option.
3. 3Use sunscreen as well. Vitamin C complements sun protection rather than replacing it.

Vitamin C can be used daily, but visible effects take about three months. Take a photograph without makeup before starting, then another each month to judge changes. Choose dark or tinted packaging because vitamin C is sensitive to sun, heat and light.1

Is 5% L ascorbic acid a reasonable starting strength?

5% can be a cautious starting choice for sensitive skin, applying the general advice to begin with a low concentration. Treat it as a starting strength for tolerance, rather than assuming it offers the same benefits as 10% to 20%. For someone choosing a first serum without sensitivity concerns, 10% is the more straightforward starting point within the recommended range.1