Pores are tiny openings in the skin that release sweat and oil, but for some, they become clogged more often. Clogged pores occur when excess oil is trapped by dead skin cells, makeup, dirt, or pore-clogging ingredients, according to dermatologist Geeta Yadav, MD.

Comedogenic ingredients can worsen acne by blocking pores, making pimples more likely, especially for those with oily skin. While we don’t fully understand why some ingredients clog pores, they’re often occlusive, sitting on top of the skin and trapping oil. Dermatologist Melanie Palm, MD, explains that these ingredients can cause skin cells to stick together instead of shedding, exacerbating breakouts.

Now, let’s explore seven pore-clogging ingredients to avoid if you’re prone to acne.