How period underwear works and what to expect

Period underwear has been around long enough that the early construction problems have mostly been solved, but there's still a lot of confusion about how it actually works, what absorbency level to choose, and whether it really replaces other products. This is a straightforward explanation without the marketing language.

What's inside the fabric ¶

Most period underwear uses a layered construction. The layer closest to the skin is typically a soft knit, often cotton jersey, that pulls moisture away from the surface. Below that is an absorbent layer, usually a microfiber or bamboo blend, that holds the fluid. A moisture-resistant base layer prevents leaks from reaching outer clothing.

The quality of each layer matters. A top layer that doesn't wick effectively leaves you feeling wet. A base layer that uses a plastic film rather than a tight-weave fabric can feel stiff and uncomfortable. The construction we carry uses a tight-weave base rather than a film, which is why it doesn't have the plastic feel that put a lot of people off early period underwear.

Understanding absorbency levels ¶

Absorbency is usually described in terms of tampon equivalents. Light flow holds roughly one regular tampon's worth. Moderate holds two. Heavy holds three or more. These are approximate figures because flow varies significantly between people and across a cycle.

For a first purchase, moderate is usually the most useful starting point. It covers most of the cycle for most people and works as a backup on heavier days when you're also using another product.

Care and longevity ¶

Rinse in cold water immediately after wearing. This step matters more than the wash cycle because it removes most of the fluid before it sets into the fabric. Then machine wash on cold. Avoid fabric softener, which coats the fibers and reduces absorbency over time. Air dry or tumble on low heat.

With consistent cold-rinse and cold-wash care, the absorbency in a well-made pair should hold up for at least two years of regular use.

If you're trying period underwear for the first time, it's worth starting with one pair before buying several, so you can see how the absorbency and fit work for your body before committing to a full set.