Vitamin C is one of THE best researched skincare ingredients
It has been proven to help with many skincare concerns, including reducing the intensity of brown spots, evening skin tone, and stimulating collagen.
Vitamin C has the ability to penetrate deeply into the skin
Many skincare ingredients contain molecules that are too big to penetrate the skin cells, but vitamin C molecules are small enough to get deeper into the skin to do their work.
Ascorbic acid (AA) is the active form of this ingredient and the primary subject of most vitamin C studies. It’s the golden standard in terms of skin penetration and ability to do all the 'magically' things vitamin C is touted to do.
Just because it's an effective ingredient doesn't mean more is better.
Studies have shown that the ideal concentration of AA is 10%-20% for maximum results. Higher than that and results do not change, but the potential change of irritation increases.
Ascorbic acid can be extremely irritating, especially in high concentrations since it needs to have a low pH to be stable and can cause stinging and redness.
Using AA with other antioxidants, like vitamin E and feurlic acid can help make it more stable, as well as the bottle it’s stored in.
But just because a product contains ascorbic acid on the ingredient list doesn’t make a product “the best.”
A well formulated product based on other vitamin C derivatives could be better than a poorly formulated product based on ascorbic acid.
Vitamin C Derivatives
To solve the issues with AA's instability, vitamin C derivatives are becoming popular alternatives. They don’t have the same oxidation problem and are less irritating on the skin. The only problem is not all vitamin C derivatives can penetrate the skin effectively, or have the same effect as AA.
As a result, there are fewer positive study outcomes and less reliable data on vitamin C derivatives. That said, many experts will agree there is promising information on a select few, which include:
- Magnesium Ascorbyl Phosphate
- Sodium Ascorbyl Phosphate
- Tetrahexyldecyl Ascorbate
- Aminopropyl Ascorbyl Phosphate
What's the best way to add vitamin C into your routine?
Vitamin C can be used either in the morning, evening or both. It can't be ‘washed’ off and remains in the skin for up to 3 days (good to know, if you miss a day!). That said, some studies show that for maximum effectiveness, vitamin C should be reapplied every 8 hours to maintain an ideal concentration in the skin, but let’s be honest that’s not realistic!
Experts debate whether vitamin C is best applied AM or PM. Since it does remain on the skin, applying it at night will still offer sun damage protection for the day time, but Vitamin C also does not play nicely with a lot of active ingredients (like retinol, AHAs etc. (which are often used at night) and so for this reason, I always recommend to use it in the morning. Apply it on clean skin, under your moisturizer with SPF over top.
How long does it take for vitamin C to work?
It will take approximately 6-12 weeks to see a significant change, depending on the type and concentration of vitamin C used.