You know those squishy globs of blood that sometimes appear when you have your period? The ones that make you wonder if you’ve shed way more than just your uterine lining? Those are period blood clots, and they're actually quite common during menstruation.
“Period blood clots are basically a mass of blood mixed with the tissue of the uterine lining and other blood cells,” explains Jessica Ryniec, M.D., a reproductive endocrinologist and infertility specialist at CCRM Fertility in Boston. “They form when blood pools in the uterus or vagina and coagulates.” Coagulation (or blood clotting) is when blood transforms from a liquid into a gel-like substance.
“Any time blood sits in one location without actively flowing, it coagulates and turns into a clot,” says Dr. Ryniec. “It’s the same mechanism by which someone stops bleeding when they have a cut.”
Although Dr. Ryniec confirms that period blood clots “can be a normal part of menstruation,” there are cases where these jelly-like lumps might suggest something more serious. “If [the blood clots] are small (like less than a quarter size) and of a limited amount, this can be OK,” assures Dr. Ryniec. But period blood clots could signal a health concern if they’re “larger [than a quarter size]” and paired with “heavy menstrual bleeding or moderate to severe pain.” Experiencing “large clots throughout the entire length of menses” also warrants a doctor’s appointment for further investigation. 
The fibroid-clot connection
One medical condition that can be connected to period blood clots is uterine fibroids, which are common growths on the walls of the uterus. While these growths are usually benign tumors, they can cause heavy bleeding and/or painful periods. There are four types of fibroids, but Dr. Ryniec points out that “a specific type, called a submucosal fibroid, may lead to heavier bleeding and therefore period blood clots.”
The reason this occurs is because “this type of fibroid is present within the cavity of the uterus, disrupting the normal endometrium (aka the inner uterine lining) and possibly leading to prolonged bleeding.” As for the other three types of fibroids, “they may also lead to blood clots because if they impact the ability of the uterus to contract and constrict the blood vessels reducing flow. Then bleeding may be heavier/prolonged and clots may be more apparent,” says Dr. Ryniec.
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Since most fibroids are asymptomatic, it’s important to pay attention to your period blood clots, especially if you’re experiencing heavy and/or painful periods. Other symptoms to keep an eye out for include “bladder pressure/frequent urination, pelvic/abdominal pressure/pain/bloating, pain with intercourse, constipation or rectal pain, or feeling a mass (the fibroid) in the abdomen,” says Dr. Ryniec.
When do period blood clots need medical attention?
Large, frequent period blood clots could signify several different medical conditions, so monitoring your menstrual flow is always a good idea.
In addition to uterine fibroids, your period blood clots might signal an abnormal hormone issue like a thyroid disorder or PCOS. Other potential conditions include “a bleeding disorder such as Von Willebrand disease, adenomyosis, endometrial polyps or other uterine cavity abnormality, and abnormal cells in the uterus including hyperplasia and endometrial cancer,” says Dr. Ryniec.
“Anytime someone experiences a change in their bleeding — an increase in [blood clot] size, frequency, or length of time seeing blood clots during their period — they should reach out to a healthcare provider,” she advises.
A good way to gauge if your period blood clots are beyond the normal range is if you're bleeding so heavily that you need to change a pad or tampon every one to two hours. (If you’re “experiencing flooding through clothes/needing to sleep with a towel, says Dr. Ryniec.) Also, if you’re frequently passing clots larger than a quarter, if your periods last more than seven days, or if there is significant pain while menstruating, definitely make an appointment with your physician.
Treatment options for period blood clots
If you're seeing your healthcare provider for large, frequent period blood clots, they'll first focus on diagnosing or ruling out serious conditions. “The main thing is identifying and treating a cause if possible which can mean medical or surgical management,” says Dr. Ryniec.” In the case of uterine fibroids, there are multiple medication and surgical options, so your physician will help you determine a treatment plan depending on the size of your fibroids and your symptoms.
But, if there is no underlying cause for your period blood clots and/or heavy bleeding, Dr. Ryniec says they can be treated with hormones like the birth control pill, patch, ring, or a progesterone intrauterine device (IUD). Other options include “medications that help the blood clot so that blood flow is decreased.” In addition, “NSAIDs like Advil, Motrin, and ibuprofen may also help, and there are also surgical options such as endometrial ablation or hysterectomy,” says Dr. Ryniec. Talk to your healthcare provider to determine the best treatment choice for you.
Sarene Leeds holds an M.S. in Professional Writing from NYU, and is a seasoned journalist, having written and reported on subjects ranging from TV and pop culture to health, wellness, and parenting over the course of her career. Her work has appeared in Rolling Stone, The Wall Street Journal, Vulture, SheKnows, and numerous other outlets. A staunch mental health advocate, Sarene also hosts the podcast “Emotional Abuse Is Real.” Subscribe to her Substack, the Critical Communicator, and follow her on Instagram, BlueSky, or Threads.
