We’ve all seen that sponsored video on Instagram. You know the one: the guy with permanent marker facial hair pulling out a sewer of blackheads using some kind of Tony Stark-approved peel-off mask. Turns out he may well be shedding much more than zits, though (and sadly, we don’t mean his beard).

Talking to skincare science site Harley Street Emporium, Dr. Zara Kassam explained just how bad peel-off masks can be. While the full process gives the illusion of a blemish-free face, it’s only the top layer of blackheads that are removed: the pus underneath still remains to fester in your face. Nice.

“The problem with these masks is clogged pores. They promise that they’ll unblock pores but they actually cause acne related problems,” says Kassam. “This is very common; we see it all the time.”

Plus, the masks are a surefire way to rid our pores of oil – the good stuff. This keeps the skin hydrated and balanced, and by removing this essential fluid, our skin works overtime to replace it, and often makes an excessive amount in the process. Which, unsurprisingly, means more blocked pores and spots.

So the next time you’re sucked in by some clever viral marketing, ignore the bloggers and stick to the science.