What happens to clots with period underwear?

November 5, 2025

Have you ever noticed blood clots while you’re on your period? They tend to show up on your heaviest days, and if you usually have a heavier flow, you may see them more often.

Menstrual flow clots can feel confusing or even a little alarming, especially if you’re switching from a tampon or pad to period underwear for the first time.

You may be wondering, how does fabric handle something semi-solid? Does it work the same way as a pad? Let’s break it down so you know exactly what to expect.

What are period clots?

Blood clots are a normal part of your menstrual flow. It's blood in a semi solid form that comes from the body's natural process of shedding the uterine lining.

What causes period clots?

When the lining of the uterus breaks down during each menstruation cycle, tiny blood vessels bleed. To prevent losing too much blood, the body releases proteins that help the blood coagulate. Sometimes, though, this system works a little slower and some of the blood forms visible clots. Not all blood clots are the same.

While some clotting is completely normal, factors like hormonal changes, heavy menstrual bleeding, or conditions such as uterine fibroids can make clots more frequent or noticeable. If you ever experience large clots (about the size of a coin or bigger) and your doctor doesn’t already know, it’s a good idea to let them know so they can assess your cycle thoroughly.

How does period underwear work?

Period underwear, also called period pants or menstrual underwear, absorbs blood just like a disposable pad without all the hassle that comes with wearing a pad. It is made with layers of moisture-wicking fabric that contain thousands of small fibers. These fibers pull liquid away from your skin, absorb it, and lock it in. The absorbent core is sandwiched between a top and a bottom layer specially designed to keep you feeling dry and odour free throughout the day.

Can period underwear handle clots?

A reusable period underwear works well with people who have heavy menstrual flow and experience blood clots frequently.

The moisture wicking layer absorbs fluid from around the clots just as it would with a disposable or reusable pad and then what would remain is the semi solid part that can't be broken down by the fabric. You can sometimes find the residual semi solid part of the clot visible on your period underwear.

So if you go to the bathroom and notice a bit of tissue or clot residue on the underwear, that’s completely normal. Just use some toilet paper to gently wipe or tap the area and remove any excess before you continue your day. If you are someone who experiences heavy bleeding and notice clotting often, you should invest in a heavy flow period underwear that is extra absorbent for your cycle.

How is the Asan period underwear a good solution for clots?

At Asan, we spent over two years on research and development to create the highest-quality leak-proof period underwear, making sure it performs even on days with heaviest flows and blood clots.

Every pair has multiple moisture-wicking, absorbent layers for quick absorption of your flow, and leak-resistant layers on the top and bottom that keep you dry and comfortable, no matter what your flow looks like.

Every body and every period is different. Whether your flow is light, heavy, or somewhere in between, period underwear is designed to handle it all with comfort and ease.

If you are thinking about which period product to use, there's no “right” product to choose. Prioritise your comfort, stay curious, and choose what helps you feel supported during your cycle.

If you are interested in looking for climate friendly alternatives for your menstrual products, read this article about switching to reusable period products.

Frequently Asked Questions

How to know how much blood can a reusable period underwear can absorb?

Every period underwear brand should share details about its absorbency, so always check the product description on the website.

Asan’s heavy-flow period underwear contains four absorbent layers and can hold up to four times more than a regular pad. You can wear it for up to 12 hours without feeling damp or experiencing any odour.

How do I clean menstrual flow clots from period underwear?

If you notice a blood clot on your period underwear, that’s totally normal and nothing to worry about. You can grab a piece of tissue and gently wipe on the crotch of the period underwear and remove any solid parts of the clots before you go on with your day.

While washing your period underwear after use, gently scrub the gusset to remove any residual clots on the surface.

Will my period pants leak if I have period blood clots?

Your period pants won’t leak just because you have blood clots.

The gusset in your period underwear is made of multiple absorbent layers that pull in the liquid part of the clot, leaving only the solid portion on the surface, which you can easily wipe away with a tissue.

However, if you’ve been wearing your period underwear for more than 12 hours on a heavy-flow day, it’s a good idea to switch to a fresh pair for the best comfort and protection.

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