A wax that comes from the oil-glands of sheep (seriously, you can't make this stuff up), lanolin is commonly found in heavy balms and ointments. Because its composition is similar to that of our skin's natural oil, it's great at preventing moisture loss and healing chapped skin, but that also makes it a heavy, occlusive ingredient that has to potential to cause comedones, notes Arch.

"Mineral oil has a large molecule that's meant to create a seal on the skin," explains Rouleau. "This makes it beneficial in some circumstances, such as when it's used in hand creams, but I suggest people who are prone to clogged pores avoid using it on their face." It's typically found in heavy, rich creams and moisturizers. FYI, petrolatum falls in the same boat, as both it and mineral oil are petroleum byproducts with similar pore-clogging tendencies, notes Rouleau.

Say that three times fast. "The long-chain fatty acid is a common ingredient in moisturizer and tends to be comedogenic," says Arch. There's also isopropyl myristate, another long-chain fatty acid. Used as an emulsifier in many moisturizers, it's in prescription Retin-A, and the reason why some people may get blackheads from using the treatment, according to Rouleau.

The heavy-hitting hydrator contains lots of oleic acid, a type of fatty acid that's yet another potential pore-clogger, according to Arch. And while it's not especially common in skin care (mostly because it is so rich and heavy), it often makes an appearance in hair products, especially those made for curly hair. Battling bacne? Check the ingredients in your conditioner; any residue that's not thoroughly rinsed off can sit on your skin, where that heavy cocoa butter can cause clogged pores.

Look, we love it too, and it admittedly has lots of great beauty benefits, but this is one oil that's best to leave off your face, especially if you're prone to pimples. It's one of the heavier oils out there, making it more likely to block pores, says Arch. If you like using straight up coconut oil, consider reserving it only for those especially dry areas below your chin, like elbows, knees and heels.