Sometimes, the occasional pimple just, well, happens—even those with an immaculate skin care regimen can face some blemishes from time-to-time. But if your irritation seems relentless or your clogged pores just won’t let up, there’s another avenue worth exploring: your hair care products. Specifically, her research suggests that residue from shampoo and conditioner can remain on the forehead, cheeks, scalp, and back for up to two hours1. And for styling products (think leave-ins and curl creams), that residue remains for up to four. That’s a pretty big window for ingredients to seep into the skin and cause some unwanted irritation. Perhaps it goes without saying: If your hair products contain iffy or pore-clogging ingredients, that two- to four-hour window can be a waving red flag for irritation.