How to Wash Period Underwear (So They Actually Last for Years)

Here's what nobody tells you when you buy your first pair of period underwear: how long they last has very little to do with the brand, and almost everything to do with how you wash them. Look after them properly and one pair will quietly see you through about two years of cycles. Get two small things wrong — and most people get at least one of them wrong — and you'll find yourself wondering why a pair that used to keep you dry all day now starts leaking by lunchtime.

The good news is that caring for period underwear is genuinely easy. There's no special equipment, no soaking them in buckets overnight, no scrubbing by hand unless you want to. You just need to know which habits protect the absorbent layers and which ones slowly destroy them. So let's get the routine right.

The simple routine, step by step

1. Rinse in cold water first

Before anything else, give them a cold rinse — ideally soon after you take them off, but if you forget, a quick rinse before they go in the wash is fine too. Hold the gusset under a cold tap and gently squeeze the water through until it runs from red to mostly clear. This takes a minute, maybe two.

Why cold and not warm? Blood is mostly protein, and heat cooks protein — the same way an egg white turns solid in a hot pan. Warm or hot water sets the stain into the fibres and makes it far harder to lift out. Cold water keeps it loose so it rinses away cleanly. This one habit is the difference between underwear that stays fresh-looking and underwear that goes grey and stained over time.

2. Wash cool and gentle

Once rinsed, they can go straight in with the rest of your laundry — there's no need to wash them separately for hygiene reasons, as long as the rest of the load isn't on a hot cycle. Use a cold or cool wash (30°C is ideal) on a normal or delicate setting, with your usual mild detergent.

Two small things help them last longer: pop them in a mesh laundry bag so they don't get tangled or snagged by zips and hooks, and don't overload the machine, so they actually get cleaned properly. If you'd rather hand wash, a few minutes in cool soapy water works just as well.

3. Skip the fabric softener — this is the big one

If you remember nothing else from this article, remember this: never use fabric softener on period underwear. This is the single most common reason a good pair stops working.

Fabric softener makes fabric feel soft by leaving a thin, waxy coating on the fibres. On a t-shirt, fine. On period underwear, that coating sits right on top of the absorbent layers and seals them off — so instead of soaking liquid in, the fabric starts repelling it. The result is a pair that feels perfectly normal but suddenly leaks, and people almost always blame the underwear rather than the softener. The same goes for dryer sheets, which leave exactly the same coating. Leave both out and your absorbency stays exactly where it should be.

While we're on the subject: skip bleach too. It breaks down both the fibres and the thin waterproof layer that stops leaks reaching your clothes.

4. Air dry — never hot

When the wash is done, hang them up or lay them flat to dry. Avoid the tumble dryer, or at the very least keep it well away from high heat.

Heat is the second enemy, after softener. The leakproof barrier and the stretchy waistband don't cope well with a hot dryer — over time the heat degrades the waterproof membrane and tires out the elastic, which is exactly when you start getting leaks and a loose, baggy fit. Air drying takes a little longer, but it's the reason a pair lasts years instead of months. They usually dry overnight; near a radiator or in an airing cupboard is fine, directly on a hot radiator is not.

5. Don't iron the gusset

You almost certainly weren't planning to, but just in case: don't iron the absorbent part. The same heat rule applies. If you really want to press the legs or waistband, keep the iron away from the gusset.

The 3 biggest mistakes when washing period underwear

Almost every “my period underwear stopped working” story comes down to one of these three. Avoid them and a pair keeps performing for years.

1. Using fabric softener (or dryer sheets). Softener leaves a thin, waxy coating that seals up the absorbent layers, so they start repelling liquid instead of soaking it in. It's the number-one reason a good pair suddenly leaks — and the softener, not the underwear, is to blame.
2. Washing or rinsing in hot water. Heat sets blood stains permanently into the fibres and, over time, breaks down the thin waterproof layer. Always rinse and wash cold or cool.
3. Putting them in the tumble dryer. Dryer heat degrades the leakproof membrane and tires out the elastic, which is exactly when leaks and a loose, baggy fit start. Hang them up or lay them flat instead.

Get those three right and you've done ninety percent of the job — everything else is just a small bonus.

Does the fabric change how you wash them?

Not really — the routine above works for everything in the Floena underwear range, whether it's the breathable bamboo styles or the soft cotton brief. Bamboo and cotton are both natural fibres that prefer cool washes and air drying, so there's nothing extra to learn.

Two small notes. Bamboo is naturally antibacterial and odour-resistant, so it tends to stay fresher between washes — but it still wants a gentle wash and no softener, like everything else. And heavier styles like the sleep short hold more liquid, so they're worth a slightly longer cold rinse before they go in, simply because there's more to flush out.

If you're curious about how the absorbent layers actually work in the first place, we break it down in how period underwear works.

So how long should a pair actually last?

With this routine, expect roughly two years of regular use from each pair — often more if you rotate several pairs so no single one gets worn and washed constantly. That's the quiet case for reusables: one pair replaces hundreds of disposables over its life, which is better for your budget and for the planet. But that maths only works if the underwear keeps performing — and that comes straight back to washing them kindly.

Quick reference: do's and don'ts

Do:

• Rinse in cold water before washing
• Wash cool (30°C) on a normal or gentle cycle
• Use a mesh laundry bag
• Use your usual mild detergent
• Air dry by hanging or laying flat

Don't:

• Use fabric softener or dryer sheets
• Use bleach
• Tumble dry on heat
• Iron the gusset
• Leave them sitting wet and balled up for days

Frequently asked questions

Can I put period underwear in the washing machine?

Yes. Period underwear is machine washable. Rinse them in cold water first, then wash on a cool cycle (30°C) with your normal detergent, ideally in a mesh bag. There's no need to wash them separately as long as the load isn't hot.

Why has my period underwear stopped absorbing?

The most likely cause is fabric softener or dryer sheets, which leave a coating that blocks the absorbent layers. Washing a few times without any softener usually restores most of the absorbency.

Should I wash period underwear in hot water?

No. Always rinse and wash in cold or cool water. Hot water sets blood stains into the fabric and, over time, damages the waterproof layer and elastic.

Can I tumble dry period underwear?

It's best not to. Heat from a tumble dryer breaks down the leakproof barrier and weakens the waistband elastic, which shortens the life of the pair. Air dry by hanging or laying flat instead.

How long does period underwear last?

With cold rinsing, cool washing, no fabric softener and air drying, a pair typically lasts around two years of regular use. Rotating several pairs makes them last even longer.

Do I need a special detergent?

No. A normal mild detergent is perfect. What matters is what you leave out — no fabric softener and no bleach — rather than buying anything special.

About the author
Mia Hartman is a content writer at Floena who covers period care, sustainable living, and feeling at home in your body. She believes periods deserve an open, shame-free conversation — and that the right products should quietly fit into your life, never interrupt it.