Our clients don't hold back:
Vitamin C in the ascorbic acid form is the most effective topical antioxidant by a very wide margin. (For clients interested, the second most effective is green tea extract as provided in our AHA cleanser.)
No other antioxidant is proven to be as clinically effective at reversing signs of environmental stressors like UV and pollutants exposure or is proven capable of encouraging natural collagen production. Most clients see a boost in evenness and brightness to their complexion within the first week of use.
The noticable fading of visible dark spots or hyperpigmentation can take a month or the full 60 day course.
We recommend at least 2-3 treatments per year with this full-potency ascorbic acid to maximize results through continuous use for ongoing correction and protection is of course ideal. Clients are encouraged to document their skin's progress using the Setlist App.


All Protocol serums are created and bottled in a 100% oxygen-free and light-free environment, using patented aerospace containment technology.
Why has no one else done this? Because it's really, really hard. Another skincare CEO famously called it "unrealistic." Our engineering team loved that.
Protocol's founding team had to look outside the skincare industry, in the aerospace and nuclear industries, to find the technology that could make oxygen-free and light-free bottling possible. The final result is 10% ascorbic acid delivered to you exactly as nature intended it: pure and perfect.
Frequently Asked Questions
Serums containing "ascorbyl palmitate," "tetrahexyldecyl ascorbate," "magnesium ascorbyl phosphate,"...etc. are all legally allowed to be called "Vitamin C serums," though these derivative forms have little-to-no actual Vitamin C antioxidant power on their own. The ingredient you're looking for is l-ascorbic acid, which is the pure, natural, full-potency form of Vitamin C you'd find in a freshly picked orange. This is also the form that will show the greatest visible benefits to your complexion. We include some derivative forms on top of l-ascorbic acid since your skin has some capacity to store these forms for later conversion to the real deal.
The second thing to note is that if your Vitamin C serum doesn't smell sweet and looks like light yellow apple sauce, it's no longer Vitamin C. There's a lot of talk out there about "stabilized Vitamin C" created by adding water or ferulic acid. These indeed slow degradation a bit, but if the serum is bottled with oxygen exposure, every hour it sits on the shelf it will continue to oxidize, degrade and lose its effectiveness significantly. If you read the fine print of most of the popular ascorbic-acid serums on the market, you'll see a plea saying "don't stock up."
All Protocol serums are created and bottled in a 100% oxygen-free and light-free environment, using patented aerospace containment technology.
Because it's really, really hard. Another skincare CEO famously called it "unrealistic." our engineering team loved that.
Protocol's founding team had to look outside the skincare industry, in the aerospace and nuclear industries, to find the technology that could make oxygen-free and light-free bottling possible. The final result is 10% ascorbic acid delivered to you exactly as nature intended it: pure and perfect.
The secret that brings it all together is what we call our "little orange ingredient fortress".
A proprietary, clinical-grade, totally airless, and UV proof bottle that's built like the space shuttle to protect our advanced and fragile ingredients. The quality of the product it delivers will be apparent from the first pump.
Because it smells like hot dogs. And because your skin can't use that much Vitamin C.
Ferulic acid is primarily added to ascorbic acid serums in an attempt to extend the shelf life of a highly unstable serum. Unlike the popular (expensive) CE Ferulic Acid ascorbic acid serum, we do not have this problem––since our serums are bottled without oxygen exposure and using an airless bottle. Ferulic acid also boosts the sun protective properties of ascorbic acid––but nowhere close to what you can get by simply applying sunscreen (which you should do anyway!). As documented by ResearchGate, the most important component of topical ascorbic acid effectiveness is its pH (it must be below 3.5). This study also shows that at a proper pH (like the Protocol Vitamin C Superserum at 3.4), the skin reaches a saturation point where it cannot take on more Vitamin C after just a few days of application. Based on these recommendations, we have lowered the concentration of our serum to 10% ascorbic acid, which allows for total antioxidant saturation but with a gentler daily application. In other words, 20% is more harsh and goes to waste anyway after day 3 of use.
Vitamin C (in the ascorbic acid form) is the most powerful topical antioxidant on Earth. As an antioxidant, Vitamin C combats environmental stressors, like UV light and pollutants, that can cause the breakdown of collagen in your skin and dark spots to form. What does this mean for your skin? Vitamin C fades dark spots, brightens dull skin, builds a more even complexion, and encourages collagen creation for plumper smoother skin.
Absolutely! In fact, the best way to use a Vitamin C serum is to apply it every morning, followed by sunscreen and/or moisturizer. Daily application (or at least 4x per week) ensures you are actively protecting your skin against the build-up of environmental stressors.
With Protocol's Vitamin C Superserum, we guarantee visible improvements within 60 days, though some users see results in as little as two weeks. A boost to your skin's brightness and evenness typically happens right away, while the permanent fading of dark spots or hyperpigmentation can take multiple courses. We recommend at least 2-3 treatments per year to maximize and maintain results.