Why pores seem to grow in size over the course of the day

Pores are among the most confounding things on the planet (right alongside quantum physics and taxes). Can you really shrink them, or not so much? How do you get those stubborn blackheads out? Why are they always accumulating gunk?

While reading a Reddit skin-care thread, one user posed yet another question about those teeny holes in your skin: Why do your pores seemingly get larger by the afternoon, yet smaller when you wake up? Cue that thinking face emoji. I’ve noticed it to be true—I wake up with a pretty calm, smooth complexion, but things just get out of control as the hours roll by. Why?

As it happens, pores aren’t exactly changing in size at all—but the illusion happens for a biological reason. “Pores don’t actually physically change size, but they may look bigger as they accumulate oil throughout the day,” says Purvisha Patel, MD, a board-certified dermatologist and founder of Visha Skincare. “They tend to look bigger when exposed to heat or steamy conditions and shrink with cold conditions, but they do not grow.”

Essentially, the oil glands accumulate sebum, which then makes the pore’s appearance change—hence the common confusion. You can combat seemingly large pores, though. “Good oil-busting exfoliating cleaners such as Visha Skincare Advanced Purifying Cleanser can help,” says Dr. Patel. “Salicylic acid, glycolic acid, lactic acid, tea tree oil, and zinc help exfoliate the tops of pores and shrink the oil production, making them stay small throughout the day.”

Toners can also have this effect. “Another way to combat the appearance of large pores is to use toner daily or twice daily based on your level of oiliness,” says Tony Nakhla, MD, a board-certified dermatologist and founder of Eighth Day. “Toners like Eighth Day Facial Tonic have astringent effects and pore-refining ingredients to tighten up pores and prevent them from getting clogged.” Look for ingredients like AHAs to achieve these effects—and you can give the illusion of perfectly tiny pores 24/7.

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