In fact, according to board-certified dermatologist Angelo Landriscina, M.D., on TikTok, niacinamide might be the “surprising thing that could be irritating your skin.” Not nearly as fun as its aforementioned accolades but important to dissect nonetheless. 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 easygoing 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.