Period Panties 101

Period panties are a popular go-to for people who want to free bleed or are tired of old standbys, like tampons and pads. Still, the idea of bleeding into your undies might make you skeptical. How exactly do these panties work? Are they comfy? Do they stay dry?

We dug into the science of period panties to come up with answers:

How do they work?

Unlike standard undies, period underwear is designed with extra layers in the crotch area to soak up menstrual blood. For example, THINX undies are built with four layers that wick away wetness, absorb menstrual flow, and guard against leaks and odors.

Other popular brands, like Dear Kate, come with fewer layers, but still promise to protect against against leaks, stains, and odors. Dear Kate claims its soft, breathable Tactel® fabric dries eight times faster than cotton and is three times as strong.

Most menstrual undies come in a variety of styles, including thongs, hipsters, briefs (even yoga pants!), and are machine washable.

How do they feel?

You might think the extra layers would feel bulky and diaper-like. But reviewers over at the New York Times said the underwear’s light synthetic materials felt comfy — and kept them dry, even after hours of free bleeding. They rated THINX and Dear Kate the best.

Do they replace tampons and pads?

Maybe. It really depends on whether your menstrual flow is light, heavy, or somewhere in between.

THINX’s typical period undies hold two regular tampons worth of flow. A thong-style version holds far less. For some of us, period panties might be a comfy solution for lounging around the house, but not for a full workday.