Menstrual clots are jiggly blobs of blood cells, uterine lining, and blood proteins that the uterus releases during menstruation. Most women get them, and for the most part they’re nothing to sweat about.

Blood clotting is actually a defense mechanism that helps your body prevent too much blood from leaving. (It can happen any time you have a cut or injury.) Menstrual clots generally happen at the very beginning of your period, when Ms. Flow is at her heaviest.

Clotting isn’t always a sign something’s wrong, but sometimes it can signal an underlying medical condition. If you’re concerned about your menstrual clots, it’s a good idea to talk to your doctor.

Normal menstrual clots are small (no bigger than a quarter) and infrequent. (PSA: Menstrual clots are totally different from blood clots that occur in your veins and arteries. At ease, menstrual maven!)

A normal clot:

  • is usually bright or dark red
  • is no bigger than a quarter
  • typically occurs at the start of your period

If your menstrual clots occur frequently and are larger than a quarter or if your period is super heavy and accompanied by large clots, see your doctor. (A “heavy” period usually means you have to change your tampon or pad every 2 hours for several hours.)

If you think you might be pregnant and your body is releasing clots, see your doctor immediately, because it could be a sign of a miscarriage.

We’re so glad you asked. During your period, your body sheds its uterine lining (aka endometrium), which leaves your body like it’s got a plane to catch.

In response, your body creates proteins that make the blood in your uterus coagulate, which in turn stops the blood vessels in your endometrium from bleeding out like an open wound.

Back story

Throughout the month, estrogen levels cause your uterine lining to expand and thicken in preparation for a fertilized egg. (Yes, it’s a presumption on the part of estrogen.)

If you don’t get pregnant, your hormones throw your uterine lining a goodbye party: your period.

During your period, your body pushes out:

  • uterine tissue
  • mucus
  • blood
  • blood byproducts

This messy assortment leaves your uterus through your cervix (the opening of the uterus) and straight through your hoo-ha, just in time to ruin your white sheets.

When your blood flow is heavier and quicker than your body’s ability to assemble an anti-clot militia, voila — you get menstrual clots.

Though menstrual clotting is normal, clots on their own can sometimes be a sign that something else is going on.

See a doctor if your clots are:

  • frequent
  • accompanied by severe pain
  • larger than a quarter
  • accompanied by a really heavy flow (requiring a new tampon or pad every 1 to 2 hours)

Some conditions than can cause clotting include:

  • fibroids
  • uterine obstructions
  • endometriosis
  • cancer
  • hormonal imbalance
  • adenomyosis
  • von Willebrand disease
  • miscarriage


Fibroids are generally noncancerous tumors made of muscular or endometrial tissue that form in the uterine wall.

They can cause:

  • heavy or irregular menstrual bleeding
  • irregular spotting
  • fertility problems
  • bloating
  • lower back pain
  • pain during sex
  • a protruding stomach

Fibroids create blockages in your uterus that can prevent blood from being released as quickly as it should, which gives it more time to clot.

As icky as these sound, they’re more common than you’d think. Up to 80 percent of women get fibroids at some point in life. Though doctors have yet to find out why, hormones and genetics are likely key players.

Uterine obstructions

Certain conditions put too much pressure on the uterine wall, which can lead to increased clots and bleeding. Obstructions (like fibroids) can prevent your uterus from contracting properly.

This causes blood to pool and eventually clot inside your uterus before being released out of your vagina.

Examples of uterine obstructions include:

  • endometriosis
  • cancerous tumors
  • fibroids
  • adenomyosis


Endometriosis is a condition that causes your uterine lining to grow outside your uterus, which can lead to an array of unpleasant symptoms that usually worsen around your period.

Symptoms include:

  • very heavy periods (menorrhagia)
  • painful periods
  • severe cramps during your period
  • pain during sex
  • pelvic pain
  • infertility
  • lower back pain
  • unusual bleeding, with or without clots


This is rare, ladies. But certain uterine and cervical cancers can lead to heavy periods and menstrual clots.

Hormonal imbalance

A healthy uterine lining — one that can thicken and grow as it’s meant to — depends on a healthy balance of the hormones estrogen and progesterone. If there’s an imbalance, you may have a heavy period.

Reasons you may have a hormonal imbalance include:

  • stress
  • menopause
  • perimenopause (the phase before menopause starts)
  • intense weight fluctuations

An irregular period is one of the primary symptoms of a hormonal imbalance. If your periods are longer or shorter than usual or if you stop having them altogether, talk to your healthcare provider.


Adenomyosis is a condition where the uterine lining grows into your uterine wall. This can make your uterus double or triple in size, which can cause a much heavier period.

Other signs of adenomyosis include:

  • spotting between periods
  • a feeling of pressure on your bladder and rectum
  • pain during sex

And — you guessed it — a heavier period makes blood clots more common.

Von Willebrand disease

Von Willebrand disease (VWD) is a chronic condition that prevents blood from clotting as it should.

VWD might be the cause of your menstrual clots if:

  • you often have heavy periods
  • you bleed easily after a small cut
  • your gums bleed easily

If you think you may have VWD, see your healthcare provider.


Miscarriages are quite common, and many of them happen before a woman even knows she’s pregnant. During a miscarriage, depending on how far along the pregnancy is, many blood clots are likely to form. Cramping and heavy bleeding are also likely.

Because miscarriages often happen before a pregnancy is detectible, it’s easy to mistake one for your period.

Women whose periods are extremely heavy (requiring a new tampon or pad every 1 to 2 hours) or who have frequent large clots run the risk of developing an iron deficiency.

Chronic iron deficiency (aka anemia) happens when your body’s red blood cells are depleted.

Other symptoms of iron deficiency are:

  • shortness of breath
  • overall feeling of weakness
  • fatigue
  • paleness
  • chest pains

If this sounds familiar, go see your doctor for a proper diagnosis.

To get to the bottom of your menstrual clots, your doctor will most likely ask about your menstruation history.

Questions they may ask include:

  • Have you ever had pelvic surgery?
  • Have you ever used, or are you currently using, birth control?
  • Have you ever been pregnant?

It’s also likely your doctor will give you a blood test to check your hormones and an imaging test (ultrasound or MRI) to check for endometriosis, fibroids, or other obstructions. They may also want to do a uterine exam.

Birth control

Hormonal birth control can help prevent the growth of the uterine lining. An IUD can reduce menstrual bleeding by up to 90 percent (and sometimes stop it completely). The pill can also reduce bleeding, though not by as much.

The less you bleed, the less likely it is you’ll form clots. Plus, hormonal birth control helps slow down the growth of uterine obstructions such as fibroids.

Some women can’t or prefer not to take hormonal birth control and instead opt to use the medication tranexamic acid (Lysteda, Cyklokapron), which also affects blood clotting.

Surgery: Dilation and curettage (D&C)

Dilation and curettage (D&C) is a procedure often associated with miscarriage. It’s usually done under sedation and involves widening the cervix and scraping out the uterine lining.

A D&C is sometimes used to treat other conditions or to determine the cause of extremely heavy periods. Women with fibroids or other uterine growths who haven’t had success with other medications may also need surgery.

If the growths or fibroids are small, laparoscopic surgery may be possible. If they’re especially large, a different surgery called a myomectomy may be required.

In the most extreme cases, a woman may choose to have a hysterectomy, a procedure that removes the uterus.

As always, talk to your healthcare provider about all your options and concerns. They’ll help you determine the best course of action for you.

Heavy periods can make life feel… well, heavy. Besides making you tired and crampy, they can make day-to-day activities uncomfortable.

These tips may get Ms. Flow to check herself:

  • Wear a tampon and a pad at the start of your period, when you’re bleeding the most.
  • Know where the bathrooms are when you’re out and about.
  • Eat nutritiously and drink lots of water. Also, try to eat iron-rich foods (like meat, tofu, quinoa, and dark green leafy veggies) to make up for the iron you’re losing during your period.
  • For peace of mind, don’t wear light-colored pants lest they betray you.
  • Have an arsenal of tampons and pads with you wherever you go.
  • Sleep on top of a thick towel or waterproof padding to avoid waking up on the set of “Jaws.”
  • Take over-the-counter anti-inflammatories like ibuprofen on the heaviest days of your period. These can provide some relief from cramping and can reduce blood loss. (FYI: Don’t take these medications if you have von Willebrand disease.)

Menstrual clots are a normal part of the menstrual cycle, and most women get them. Sure, they’re annoying, jiggly little underwear-wreckers, but they’re generally considered harmless.

If they show up often, are larger than the size of a quarter, or are accompanied by pain and/or very heavy periods, go see a healthcare provider to rule out any medical issues.