Let me just say: Niacinamide itself isn’t known to be irritating; in fact, most people find it very tolerable, as opposed to potent acids or retinol. Rather, it’s niacinamide overload that can pose problems, as you don’t need a super-high concentration to reap its advantages. “Most niacinamide studies use 2% to 5% of the ingredient,” cosmetic chemists Victoria Fu and Gloria Lu previously wrote for mbg. “There’s no reason to think 30% niacinamide is six times as effective as 5% niacinamide. You’re more likely to irritate your skin with ultra-high concentrations than anything else.” While the B vitamin is beloved for strengthening the skin barrier, too much of it can actually lead to sensitivity, skin irritation, and redness—but if you stick to a 2 to 5% concentration, you should be set.
Here’s where things get tricky: Niacinamide has quickly become the crown jewel of skin care, given its bundle of benefits (moisture! Oil control! Brightness!), and brands are formulating with it at breakneck speed. “You could be getting higher percentages of niacinamide than you think you are, because it’s included in a lot of products,” Landriscina explains.
It’s also one of the most easy-going actives out there—it even pairs well with notoriously finicky vitamin C. “So brands often throw it into products as an extra,” adds Landriscina. But that “extra” hit of niacinamide can easily tip the scales from nourishing to irritating, especially if you’re piling on forms of vitamin B3 without even knowing it.