Pores: We’ve all got these tiny openings in our skin for releasing sweat and oil, but for some people, they can be more temperamental than others. Or, rather, clogged pores happen more often to some of us than others. Clogged pores happen when oil doesn’t or can’t flow through them as it should, explains board-certified dermatologist Geeta Yadav, MD.

“Typically, this is caused by the overproduction of oil that then becomes trapped by dead cells that haven’t properly shed from the lining of the pore. Makeup, dirt, and/or comedogenic ingredients can also block the pore, and prevent that flow of oil through it,” she says.

Comedogenic is essentially a word for pore-clogging, and while these types of ingredients aren’t the sole cause of acne and breakouts—there are several factors—they certainly won’t help the situation. “Pore-clogging ingredients make it much more likely that pimples will form,” says board-certified dermatologist Rachel Nazarian, MD.

“In someone who has naturally oily skin or who harbors the bacteria that causes acne, using these ingredients is like adding gas to the fire. It’s a dangerous combination that can exacerbate acne and cause consistent breakouts.”