Period clots: How much clotting is too much?

Everything you need to know about period blood clots

  • Not to be confused with venous or thrombosis clots (the kind that can form in your veins and cause serious problems), period blood clots are perfectly normal and usually nothing to worry about
  • Normal period clots are smaller than a quarter and red, brown, or black-ish in color; they show up occasionally and are most common on your period’s heavier days
  • Keep an eye on your flow: Abnormal clots tend to be larger than a quarter and may be grayish in color – and they may also be accompanied by heavy bleeding or unusual pain

Why do you have blood clots on your period? 

Is your period clotty by nature? Seeing a blob of slimy, gelled blood during your period might freak you out, but menstrual clots are actually very common and, in most cases, nothing to be worried about. 

Period clots happen because, during menstruation, your uterus sheds more than just blood: The uterine lining (a.k.a. endometrium) that sloughs off contains a mixture of blood, blood byproducts, tissue, and mucus… apologies if you were about to eat lunch.  

This delightful mixture of bodily substances isn’t pure liquid in form – and, as your period progresses, some of the endometrial buildup will accumulate at the bottom of your uterus. Your body produces substances called anticoagulants to help loosen up and liquefy this material, making it easier to flow through the cervix and out through the vaginal canal. 

Sometimes, your body can’t produce enough anticoagulants to keep up with the amount of fluid and tissue your uterus is trying to shed.1 As a result, clumps of gel-like clots pass through the cervix (along with your usual period blood) and wind up on your pad, stuck to the side of your tampon, or collected inside your menstrual cup or disc.

There’s still some debate among the scientific community as to whether period clots form in the uterus or vagina, but we do know that they’re a common and normal characteristic of menstrual flow.2

Period clots vary in color from bright to dark red, blackish, blue- or purple-ish, or even brown – the latter being most common towards the tail end of your period. Like all aspects of your period, it’s a good idea to keep an eye on clots so you know what’s normal for you as an individual. Occasionally, large or off-colored clots can be a warning sign of a bigger issue. 

Read on to learn more about period clots and how to tell the difference between normal and abnormal clotting. 



Period blood clots: What’s normal & what’s not?

Finding a clot in your tampon, pad, menstrual cup or menstrual disc does not mean you need to rush to your doctor’s office. Normal period clots are: 

  • Smaller than a quarter
  • Occasional and usually on heavier days
  • Bright red or dark red
  • Blackish, especially if they’re larger
  • Brown, especially later in your cycle

That said, sometimes, period clots can be a symptom of another condition. Look out for period clots that are: 

  • Frequently larger than a quarter
  • Accompanied by heavier-than-usual menstrual bleeding
  • Grayish and/or happening when you think you could be pregnant (this could be a sign of miscarriage)
  • Accompanied by lots of pain that isn’t normal for your period
  • Accompanied by anemia (low iron levels) or easy bruising2

Sometimes, clots form for other reasons – including certain underlying health conditions. Knowing what’s normal for you as an individual will help you make a decision as to whether or not you should see a healthcare provider. When in doubt, it never hurts to make a quick call.



Causes of abnormal period clots

The potential reasons for abnormal period clotting are similar to those for heavy menstrual bleeding, since the two symptoms usually go hand in hand: Heavy flow usually equals more clotting and larger clots. 

Abnormal period clots can be a sign of:3

Uterine polyps or fibroids: Both benign uterine fibroids and polyps (which could potentially be cancerous) can lead to heavy menstrual bleeding and clotting.

PCOS or other hormone imbalances: Polycystic Ovary Syndrome (PCOS) and other hormonal imbalances can delay your period for months as a result of anovulation (when your body doesn’t ovulate, or release an egg). This long buildup can lead to unusually heavy periods and large period clots.

Endometriosis: Endometriosis is a disease characterized by an overgrowth of endometrial-like tissue outside of the uterus, i.e. elsewhere in the pelvis or on the outside of other reproductive organs. It can cause very heavy and painful periods with intense cramping and large clots.

Cancer: Rarely, period clots are a sign of cervical or uterine cancer. Getting regular pelvic exams and Pap smears is important for preventative screening, but talk to your doctor about any alarming changes in your period (including clots) even if you’ve recently had a negative Pap. 

Adenomyosis: Adenomyosis is a condition in which the uterine lining (endometrial tissue) grows into the muscular wall of the uterus, often causing heavy periods and blood clots.

Miscarriage: A heavy period and large clots may not be a period at all if you have unknowingly become pregnant and then undergone a miscarriage. Talk to your provider if you believe you could have been pregnant and experience sudden, unexplained bleeding with large clots, especially if the clots are white or grayish in color. 

Abnormal clotting can also be associated with certain prescription medications, especially anticoagulant drugs typically prescribed to treat conditions like deep vein thrombosis. Ironically, anticoagulants may actually increase the amount of clotting you see during your period – and they can also lead to heavier or longer menstrual bleeding.4 

Common anticoagulant drugs include: apixaban (Eliquis), dabigatran (Pradaxa), edoxaban (Lixiana), rivaroxaban (Xarelto), and warfarin (Coumadin). 

Remember: Most period clots are harmless! Always talk to your doctor if you’re concerned about clots or unusually heavy periods, but don’t try to self-diagnose (Dr. Google can lead you down some deep, dark rabbit holes) or get too stressed out before you have a professional consultation. 


How to manage period clots

Most menstruators experience occasional period clots, but for some, clotting is an every-day-of-your-period annoyance – accompanied by things like uncomfortable pad or period underwear wetness, messy period product removal, and unexpected tampon slippage (ever sneezed and felt like your tampon just shot right out of you, only to realize it did so because it was covered in slippery clots??).

If you’re just a naturally “clotty” person (nothing to be embarrassed about!), there are a few tips and tricks to control the situation. 

First, if tampons are causing you trouble, try switching to a period product that collects – rather than absorbs – your menstrual flow. Menstrual discs and cups are a great option, not only because they keep blood and clots neatly contained within a body-safe receptacle (making removal a little less messy), but they also allow you to monitor just how much blood and clots you’re shedding on a given day. 


Flex Disc and Flex Cup can both be worn for up to 12 hours at a time. On ultra heavy days, you may need to dump your cup or change your disc twice in a day, but you’ll be less prone to leaks and avoid the annoying wet-and-stickiness that comes with wearing pads or period underwear. Cups and discs offer three to four times the capacity of traditional period products. Oh, and they won’t shoot out of your vagina unexpectedly like a slippery tampon!

Heavy periods with lots of clotting can be frustrating to deal with, but as long as you’ve ruled out any underlying conditions, managing the flow is usually just a matter of choosing the right period products. 

Experiment with a few options (some folx in the Uterati fam swear by combining a menstrual cup or disc with period underwear on their heaviest days) or try switching between products to match your flow. You can also chat with your provider about hormonal contraceptive options, like the birth control pill, patch, or IUD. Some of these offer a longer-term solution to lightening or shortening your period and managing clots. 


This article is informational only and is not offered as medical advice, nor does it substitute for a consultation with your physician. If you have any gynecological/medical concerns or conditions, please consult your physician. 

Normal period clots may be bright red, dark red, brown, or nearly black in color.