Unread postby Sam W » Tue Nov 10, 2020 8:11 am
Hi potatochipeater,
Period underwear works on a similar principle to pads; the crotch of them is extra absorbent so it traps and holds period flow. The undies themselves are made from normal fabric, like cotton, which is part of the appeal for some people because it means you can just wash them with the rest of your laundry.
As for reliability, there about as reliable as pads or tampons are, because they're designed to hold a certain amount of flow. Some people find they can make it through their period using just the underwear, while others prefer to use them as back-up along with tampons or a menstrual cup.