10% Niacinamide Booster.

"Anything over 5% niacinamide has never really been studied and really never been shown to have benefit. All the studies that show niacinamide is great for skin tone, for brightening, for collagen support, for barrier support, all these different things niacinamide does, has been shown to be beneficial at the 5% concentration or less. So when you see a 10% niacinamide, you're like, do I really need 10%? It's double what the recommended amount is. The more you have of anything, the more likely you are to get irritation. It's not like the more of things the better it is. Sometimes less is more. Studies show 5% is sufficient for pretty much all your clinical endpoints. Between 10 and 15%, you're probably going to tolerate it, not that it's more effective, but the tolerability perhaps isn't terrible. But 10% is more than enough than what you need."