Vitamin C is one of the most well-researched and beneficial vitamins you can apply topically. Ongoing use has been shown to increase collagen production (including dermal collagen, which is significant for wrinkle reduction), reduce the appearance of skin discolorations, strengthen skins barrier and repair response, reduce inflammation, and help skin better withstand exposure to sunlight.[1-3]
Vitamin C comes in many forms, with ascorbic acid being the most well-researched for its efficacy. Learn more about ascorbic acid’s benefits here.
Other forms of vitamin C you will see included in skincare products include magnesium ascorbyl phosphate, L-ascorbic acid, tetrahexyldecyl ascorbate, ascorbyl palmitate, ascorbyl glucosamine, and ascorbyl tetraisopalmitate. In any form, vitamin C provides potent antioxidant protection, shielding skin from damaging free radicals. 
When incorporated into your daily skincare lineup, well-formulated products containing vitamin C can provide a range of benefits that keep your skin younger-looking, longer, such as:
- Reducing the appearance of brown spots and other types of sun damage
- Helping to boost healthy collagen production
- Reducing inflammation and irritation, both of which cause a cascade of damage
- Fading post-breakout red marks by improving skin’s natural healing response
- Increasing the effectiveness of your sunscreens and boosting your skins defense against UV exposure 
Note: All antioxidants, including vitamin C, are vulnerable to destabilizing when exposed to air and light. That means if you want to reap the reward of your antioxidant-enriched treatments, only choose those that are packaged in opaque tubes, air-restrictive bottles, or pumps that help keep their ingredients stable.
- Campos P, Goncalves G, Gaspar L. In vitro antioxidant activity and in vivo efficacy of topical formulations containing vitamin C and its derivatives studied by non-invasive methods. Skin Res Technol. 2008;14(3):376-80.
- Nusgens B, et al. Topically applied vitamin C enhances the mRNA level of collagens I and III; their processing enzymes and tissue inhibitor of matrix metalloproteinase 1 in the human dermis. J Invest Dermatol. 2001;116(6):853-9.
- Darr D, Combs S, Dunston S, Manning T, Pinnell S. Topical Vitamin-C Protects Porcine Skin From Ultraviolet Radiation-Induced Damage. Br J Dermatol. 1992;127(3):247-53.
- Farris P. Topical vitamin C: a useful agent for treating photoaging and other dermatologic conditions. Dermatol Surg. 2005;31:814-7.
- Chen L, Hu JY, Wang SQ. The role of antioxidants in photoprotection: a critical review. J Am Acad Dermatol. 2012;67(5):1013-24.