What's the Deal with Blood Clots And Your Period?

What's the Deal with Blood Clots And Your Period?

Let’s talk about blood clots. No, it’s not the most glamorous topic. But it’s one that affects a lot of us. Around 1 in 3 women have heavy periods, and that often means clots: clumps of blood with a thick, gelatinous texture. (You’re not eating while you read this, right?)

If you’ve spotted them on your pad or tampon, or in the toilet bowl, you might have panicked, or at least idly wondered if your body was falling apart. The good news is, they’re not usually a problem – but in some cases, you should seek medical treatment.

Here’s the lowdown:

What’s in a clot?

Every month, your uterus is ready to make a baby – even if you’re not. The uterus lining thickens over the course of roughly 28 days, to provide a hospitable environment for a fetus. When you don’t get pregnant, your body sheds this extra lining along with your unfertilized egg, and there you have it: your period. If your flow is heavy, your body’s natural anti-clotting mechanisms don’t have time to kick in, so what you also have is clotting.

Most clots are normal

Typically, clots are bright or dark red (it doesn’t matter which), no bigger than a quarter, and only turn up on your period’s heaviest days. They’re usually nothing to worry about. Even a period that contains more clots than usual or bigger clots than usual isn’t a problem, if it’s not a permanent change. However, if you also have symptoms of anemia like extreme fatigue, breathlessness, and heart palpitations, you should probably get your iron levels checked. And if you have debilitating pain as well as clotting, or your periods used to be lighter, it’s worth seeing a doctor.

Common causes of excess clots:

Hormonal changes

Estrogen and progesterone levels dip before a period, so your uterus knows to shed its lining. If your hormones are out of balance (perhaps because of stress, illness, or a change in birth control) this can be delayed, giving the lining more time to build up. When it’s finally released, it will be heavier and more clot-filled. If this goes on more than a couple of months, it might be time to tackle the imbalance, or its underlying causes.


As well as making uterine cells grow outside the uterus, leading to pain and scarring, among other symptoms, endometriosis also causes a thicker uterine lining to form. This means heavier periods, and for some women, excess clotting. Treatments include hormonal medication to suppress symptoms and minimally-invasive surgery.


Instead of tissue growing outside the uterus, as it does in endometriosis, with adenomyosis it burrows into the muscles of the uterine wall. This can lead to heavier, longer-lasting periods, including clots. Again, medication to balance hormones or surgery can help.

Uterine growths

Because our bodies are always looking for new and horrifying ways to surprise us, sometimes uteruses grow random protrusions when no-one asked them to. These include fibroids (lumps of tissue that cling to the uterine wall), polyps (growths formed from the uterus lining that stick out of the uterine wall), and adhesions (a build-up of scar tissue, usually from an infection or surgery). Any of them can slow down period flow, leading to an increase in clots. Hormone-blocking medication and non-steroidal anti-inflammatory drugs (NSAIDS) can shrink growths and reduce symptoms, but surgery might also be necessary.


An early miscarriage can seem like a heavy period, with clotting, painful cramps, and bleeding for days. The clots might be bigger than those you’d see during a period, or the same size. If there’s a chance you might have been pregnant, see a doctor so they can rule out a miscarriage – or make sure it’s progressing normally. If you need emotional support, the non-profit group Hope After Loss offers help in person and online.

Photo by Marianne Taylor Photography

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