ascorbic acid

Ascorbic Acid at a Glance

  • Technical name for pure vitamin C
  • Proven to reduce wrinkles and discolourations
  • Helps boost the effectiveness of sunscreens
  • The most abundant antioxidant in skin
  • Very sensitive to light and air exposure

Ascorbic Acid Description

Ascorbic acid—also known as L-ascorbic acid—has the most research of any form of vitamin C when it comes to skin, and in fact is the most abundant naturally occurring antioxidant in our skin. Concentrations between 5–20% can improve numerous the appearance of signs of ageing, including discolourations, wrinkles, and loss of firmness due to sun damage. Lower concentrations such as those between 0.3–2% also offer benefits, such as improvement of uneven skin tone, fine lines, and boosting skin’s antioxidant supply.

Ascorbic acid is also a powerhouse when mixed with other antioxidants, especially vitamin E, and is particularly great for evening out skin tone when used alone in higher concentrations, such as 15%, 20%, or greater. Vitamins C and E work together to keep each other stabilised and able to exert their benefits in skin longer.

In order to be most effective in higher concentrations, any water-based vitamin C formula’s pH should be 3.5 or lower. This helps improve stability and permeability of ascorbic acid, allowing it to do more than work as an antioxidant.

Ascorbic acid is a particularly vulnerable antioxidant when exposed to UV light and air, so it must be packaged to protect it from these elements during routine use. If not, its effectiveness will gradually become diminished to the point of not working at all. You will see this as discolouration from oxidation which causes the product to turn a copper to brownish colour. For this reason, avoid any vitamin C (ascorbic acid) products packaged in traditional, open-mouthed jars or clear bottles.

Dropper-based dispenser-type packaging should also have air-restrictive capabilities to improve stability. And for maximum potency, it’s best to use a water-based vitamin C treatment within 3 months of opening. With once-daily usage, most people will find they go through their vitamin C product within a couple months.

Considered safe as used in cosmetics, ascorbic acid is also fine to use with retinol and niacinamide without any of these ingredients causing the other to break down or lose effectiveness beyond what would normally occur due to air and light exposure, which is why ingredients like these need to be routinely applied.

Acorbic Acid References

Drug Delivery, February 2021, pages 445–453
Journal of Cosmetic Dermatology, December 2020, pages 3,262–3,269
Journal of Oral and Maxillofacial Pathology, May-August 2020, pages 374–382
Journal of Cosmetic Dermatology, March 2020, pages 671–676
Journal of Clinical and Aesthetic Dermatology, July 2017 pages 14–17
Journal of Drugs in Dermatology, July 2016, pages 863–867
Clinical, Cosmetic, and Investigational Dermatology, September 2015, pages 463–470
Indian Dermatology Online Journal, April–June 2013, pages 143–146
AAPS PharmSciTech, July 2011, pages 917–923
Journal of Drugs in Dermatology, July 2008, Supplement, pages s2–s6
International Journal of Toxicology, Supplement 2, March 2005, pages 51–111
Skin Pharmacology and Physiology, July-August 2004, pages 200–206

See ascorbyl glucoside ascorbyl palmitate glyceryl ascorbate magnesium ascorbyl phosphate tetrahexyldecyl ascorbate vitamin C

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About the Experts

Paula Begoun is the best-selling author of 20 books about skincare and makeup. She is known worldwide as The Cosmetics Cop and creator of Paula’s Choice Skincare. Paula’s expertise has led to hundreds of appearances on national and international radio, print, and television including:

The Paula's Choice Research Team is dedicated to busting beauty myths and providing expert advice that solves your skincare frustrations so you can have the best skin of your life!