The Lowdown on Period Underwear

The Lowdown on Period Underwear

Editor’s note: This article also contains affiliate links, so we earn a small commission if you choose to buy ‒ at no extra cost to you. Happy shopping!

Curious about period underwear but not sure where to start?

Period protection has come a long way since the first applicator tampon was patented in 1933.

While many people still use tampons and pads, period underwear and menstrual cups are expanding the options of how we manage our periods — with some pleasing results.

As reusable menstrual wear becomes more popular, we are seeing a significant reduction in waste.

Some people also prefer the convenience of these new forms of protection.

If you’re new to the world of period panties, don’t worry.

We’ve got you.

In this article: 📝

  • What is period underwear?
  • How does period underwear work?
  • Can you bleed through period underwear?
  • How do you know when period underwear is full?
  • Do period pants smell?
  • How often do you change period undies?
  • How to wash period underwear
  • Best period underwear for women
  • Period underwear — the bottom line 😉

What is period underwear?

Quite simply — panties that are specifically designed as period protection.

They look just like regular underwear, the only difference being the crotch area, where they have extra layers ready to take care of any liquids that come their way.

So does that mean you can simply pop on an undergarment, and it’ll take care of your flow? Well, technically, yes.

Some people choose to wear them on their own, while others use them as backup for their pads, tampons, or menstrual cups.

Reusable period underwear is eco-friendly, waste-minimizing menstrual protection.

You can wash and re-wear them, meaning they don’t land in the garbage every menstrual cycle.

They come in different absorbency levels, making them appropriate for everything from very light to very heavy flow.

There are also disposable period underwear options.

These can be used for overnight protection so that your period doesn’t worry you while you sleep.

Always ZZZ Period underwear is a popular choice.

How does period underwear work?

Period underwear is designed to keep your skin dry and prevent leaks.
It’s made of multiple layers of different fabrics.

The layer closest to you is designed to get liquid away from your skin quickly.

The next layer is made of absorbent material like microfiber polyester that creates a moisture-trapping core.

The bottom layer is all about preventing leaks.

It’s usually made of lycra or nylon.

All three layers work together to keep you dry, comfortable, and leak-proof.

Can you bleed through period underwear?

No method of period protection is 100% leakproof.

So if you want to know can period undies leak? the answer is that it is possible, just like it’s possible to leak from a pad or tampon.

For days when you’re dealing with a particularly heavy flow, it can help to double down by using another form of protection in conjunction with your period underwear.

(While you know your body best, for many people who menstruate, the second day of their period is often the heaviest.)

You may also find that on particularly heavy days, you might want to change your period underwear more frequently to prevent leaks.

It’s a good idea to have a few pairs in rotation.

How do you know when period underwear is full?

Unfortunately, period underwear does not come with a gauge that tells you when it’s reached its full capacity.

(Anyone feel like developing that technology? 🤔)

But you can usually tell if you’re reaching your limit.

The best thing to do is check to see if the side seams are wet.

This means that the absorbent layers have reached their fill.

Do period pants smell?

It’s a fair question — and one that can be difficult to ask even your closest friends.

The good news is, provided you follow the washing and care instructions, period underwear shouldn’t retain any smell.

And some brands even offer odor protection to keep you feeling fresh.

But if they’re left too long or not cleaned properly, there’s a chance you could notice an odor.

Period blood usually tends to have a scent. It may have a metallic odor due to the iron in your blood.

It might also smell a bit off as a result of the natural bacteria from your vagina mixing with the blood.

Sweat from the glands in the area can amplify the smell.

(Note that if your period blood has a very strong fishy smell, it could be the result of an infection and is worth checking out.)

To keep unwanted scents at bay, knowing how to wash and care for your period underwear is an excellent place to start.

How often do you change period undies?

That all depends on the heaviness of your flow.

Consider how frequently you change other menstrual products and use this as a guide.

Many brands advertise that they hold between one to five tampons’ worth of flow.

Some options are designed to be worn all day, while others recommend changing about every four to six hours.

So it really depends on your body, your brand, and your preferences.

As for how long a pair will last, you can probably keep them for anywhere between two and five years, provided you follow the care instructions.

How to wash period underwear

Period underwear is made to be convenient for the wearer, so luckily, the care instructions are not too difficult to follow.

Do you just wash period underwear?

Period underwear can be washed in the washing machine. 🎉

(You can, of course, choose to hand wash them if you prefer.)

The best bet is to follow the care instructions on the label to the letter.

Here are some tips on how to keep them hygienic and make them last:

  • Rinse them out in the sink before putting them in the washing machine, as this will help to prevent stains and build-up.
  • When it’s time for them to hit the machine, pop them in a mesh bag. (These come as part of the package with some brands.)
  • Wash on a delicate or gentle cycle at a cold temperature.
  • Avoid fabric softener and bleach.

Can period undies go in the dryer?

Unfortunately not.

They won’t survive more than two or three trips through the dryer.

It’s best to lay them flat or hang them up to dry.

Best period underwear for women

We’ll take you through our top three favorite brands.

Thinx Cotton Brief Period Underwear

Thinx period underwear

This very popular brand comes in a variety of absorbencies from lightest to super.

There are also a range of styles to choose from, including boyshorts, hi-waisted, french cut, and thong.

Another thing that makes this company super special is that they are actively working to fight period poverty and promote access to reproductive health.

Knix period underwear

Knix period underwear

This company has taken the period underwear market by storm.

They also have options from heavy absorbency to super light.

(Their heaviest option is advertised as absorbing the same amount of blood as up to 20 tampons. 😮)

Available in a range of styles, they have some particularly cute options available, like these lacy boyshorts.

And if you’re specifically looking for period underwear for teens, we think KT by Knix is a great choice.

ModiBodi period underwear


This company has designed their underwear offering not only for periods but also for moisture of other kinds.

Suitable for incontinence, as well as for the discharges that come with pregnancy and the postpartum phase, it works for all sorts of bodies and times of life.

Their underwear is biodegradable to help prevent textile waste, making it a real win for the environment.

Period underwear — the bottom line 😉

If you’re keen to try environmentally-friendly menstrual protection, period underwear is an excellent option.

Use it on its own or as backup for tampons or a menstrual cup.

It’s easy to care for, convenient, and a great way to prevent waste.

We’re fans.


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