Period underwear and how it works

Short answer: Period underwear has several built in layers. One draws fluid away from the skin, one absorbs, and an outer one is leak resistant. It can replace or supplement other products, depending on what your days are like.

The three layers

The innermost layer moves fluid away from the skin, so it does not feel wet. The middle layer absorbs and holds the fluid. The outer layer prevents leaks through to your clothes. Together they work as protection built into the briefs themselves. See period underwear.

Why the inner layer matters

The inner layer decides how the briefs feel. If it moves fluid on quickly, your skin stays drier, even while the absorbent layer is working. A soft material against the skin also makes the briefs comfortable to wear all day. That is why many choose a model with a soft inner layer.

Capacity varies

Models have different capacities, often stated as a number of tampons. Choose by your own days and not by an average. On light days a thinner model may be enough. On heavier days a model with more capacity gives more peace of mind. Many keep a few of each.

Finding the right fit

Period underwear should sit close, so the absorbent layer stays where it should. If it is too loose, it can shift, and the layers no longer cover the right spot. Choose your size by hip measurement, as with other briefs, and try it at home before wearing it all day.

Washing is different

Rinse them in cold water first, then wash at 40 degrees without softener. Softener ruins the absorbent layer, because it leaves a film that stops the fabric taking up fluid. Dry them on a rack, not in the tumble dryer. Read more about washing and care.

How many you need

How many you need depends on how often you want to change and how quickly you can wash. Many change once or twice a day and keep a few pairs for each day of their period. Start with a few and see how they fit into your routine.

As a backup

Many wear them as backup on light days or at night. Others combine them with a cup or a tampon for extra security. There is no right way, only the one that suits you. See also Moodies and bamboo underwear for women.

At night

At night you lie still for many hours, and fluid spreads differently than during the day. A model with more capacity and a longer absorbent area towards the back gives more peace of mind. Many choose period underwear for the night because it does not move when you turn over.

If you are unsure

If you are unsure what suits you, try it on a day when you are at home. That way you can feel how the briefs feel and how long they last. If you have questions about your period or your health, talk to your doctor.

Frequently asked questions

How does period underwear work?

Through several layers. One moves fluid away from the skin, one absorbs, and an outer layer prevents leaks through to your clothes. Together they act as built in protection.