What Blood Clots During Your Period Mean

For most women, occasional clots in period blood are normal and nothing to be concerned about. That said, it's also possible that another condition is causing abnormal blood clots to appear in your period blood.

This article is a guide to menstrual blood clots—what they're made of, how they form in your period blood, and possible signs that something else could be causing them.

When to See a Doctor for Blood Clots

Verywell / Emily Roberts

How Menstrual Clots Form

Your menstrual period starts when hormones trigger your body to shed the lining of the uterus (endometrium). As the lining sheds, small blood vessels bleed.

To prevent too much blood from being lost, your body forms blood clots using a combination of plasma (the liquid part of blood) and platelets (tiny blood cells that bind together to form clots).

Mixed into the menstrual blood are also bits of tissue from the uterine lining. Thus, what appears to be a blood clot may actually be a clump of endometrial cells. Or, it can be a mixture of both endometrial cells and blood clots.

Dark red or blackish clots may appear during the first few days of your period when the flow is heaviest. Your period may start or end with bright red blood clots, too. This means the blood is flowing quickly and doesn't have time to darken.

When your menstrual flow is heavier, blood clots tend to be bigger because there's a larger amount of blood sitting in the uterus.

In order to pass larger blood clots, the cervix has to dilate a bit, causing pain that can be quite intense. This partially explains why, if you have a heavy flow, you're more likely to have cramping.


Menorrhagia refers to heavy menstrual bleeding and menstrual bleeding that lasts more than seven days. Your flow is considered heavy when you have to change your pad or tampon after less than two hours, or you are passing blood clots that are the size of a quarter or larger.

Depending on your age and medical history, there are many conditions that could be increasing the volume of your menstrual flow and/or causing abnormally large clots to form. Some of these conditions include:

  • Uterine fibroids: These noncancerous growths in your uterus are common and can cause heavy bleeding.
  • Endometriosis: In this condition, the endometrial tissue in your uterine lining grows outside your uterus, usually onto your fallopian tubes and ovaries.
  • Adenomyosis: This is a condition in which the endometrial tissue in your uterine lining begins to grow into your uterine wall, often making your uterus larger.
  • Hormonal imbalances: Hypothyroidism, polycystic ovary syndrome (PCOS), perimenopause, and menopause can cause irregular shedding of the uterine lining, resulting in clotting and heavy bleeding.
  • Miscarriage: Pregnancy loss can happen very early, sometimes before you even know you're pregnant. Clotting and bleeding are common symptoms.
  • Cesarian scar: Some women may experience abnormal bleeding associated with the scar from their cesarian section.
  • Cancer in your uterus or cervix: Potential but less likely sources of blood clots.

If you're pregnant and passing clots, see your healthcare provider or go to the nearest emergency room. This may be a sign of a miscarriage or a potentially life-threatening ectopic pregnancy, in which the fetus has implanted outside of the uterus.

Diagnosis of Underlying Conditions

Blood clots in and of themselves aren't a medical condition, but rather a possible symptom of another underlying condition. Your healthcare provider may start trying to diagnose the cause of your blood clots by asking you some questions, such as:

  • How long does your period last?
  • How heavy is your usual flow?
  • Have you noticed changes in your flow over time?
  • Have you been pregnant before?
  • Have you ever had pelvic surgery?
  • Do you use birth control and, if so, what kind?
  • What medications are you on?

Next, your healthcare provider will do a pelvic exam. They may also want to do some tests to figure out what might be causing your blood clots. These tests may include:

  • Blood tests: A blood test can be done to look at your thyroid function and to check for a hormonal imbalance, anemia, or an issue with how your blood clots.
  • Pap test: Cells are taken from your cervix and examined to see if any changes might be the cause of heavy bleeding and/or clots.
  • Ultrasound: This painless procedure uses sound waves to monitor blood flow and check for problems like fibroids or endometriosis.
  • Endometrial biopsy: In this procedure, tissue samples of your uterine lining are removed and evaluated to look for abnormal cells. You may feel some cramping while the procedure is done.
  • Sonohysterogram: To examine your uterine lining, your healthcare provider will inject fluid into your uterus through a tube that is inserted through your vagina and cervix. During the procedure, you may feel some cramping or pressure.
  • Hysteroscopy: Your healthcare provider will insert a thin scope with a light to examine your uterus in detail. This can help diagnose polyps and fibroids.
  • Computerized tomography (CT) or magnetic resonance imaging (MRI): Whereas an MRI uses powerful magnets and radio waves to create a picture of your uterus, a CT is more similar to an X-ray. Both are completely painless procedures.

Blood Clots Healthcare Provider Discussion Guide

Get our printable guide for your next healthcare provider's appointment to help you ask the right questions.

Doctor Discussion Guide Woman

Treatment for Abnormal Clots

Your treatment will depend on a number of factors, including:

  • What's causing your large blood clots and/or heavy bleeding
  • How severe the clots and bleeding are
  • Whether or not other painful symptoms accompany your period
  • Your age, and where you are in your reproductive journey

Iron Supplements

Prolonged, heavy menstrual bleeding is a common cause of anemia in women of reproductive age. In fact, one study found that 63.4% of women who experienced menorrhagia also had anemia.

Anemia can make you feel tired, weak, dizzy, and lightheaded, among other symptoms. To treat the condition, your healthcare provider may prescribe iron tablets or supplements to restore iron levels in your blood.

Iron supplementation will not make your period lighter. However, it can remedy the symptoms of anemia and help you replace healthy red blood cells.


Certain contraceptives may reduce your menstrual blood flow and control irregular bleeding. In particular, healthcare providers may suggest hormonal IUDs or birth control pills.

Two forms of oral contraceptives are used to control heavy bleeding: combination birth control and progesterone-only birth control. Combination birth control pills containing both estrogen and progesterone can reduce your menstrual blood flow by up to 77%.

A progesterone-only pill or injection like norethindrone (also known as norethisterone) can decrease menstrual blood flow by more than 80%. Norethindrone is considered the most commonly used progesterone-only oral contraceptive.

Another option is a hormonal IUD like Mirena, which has been shown to reduce menstrual blood flow by up to 95% after one year of use. That said, you may have irregular bleeding and spotting during the first six months or more.


Taken during your period, Advil or Motrin (ibuprofen) can reduce pain, cramping, and the amount of bleeding you have by up to 49%.

Advil and Motrin both fall under the category of non-steroidal anti-inflammatory drugs (NSAIDs). But not all NSAIDs function the same exact way.

Although aspirin is another NSAID used to treat pain and inflammation, taking it can actually increase your menstrual flow.

Hormonal Therapy

Progesterone, estrogen, or a combination of the two can help reduce bleeding. These hormones can be prescribed as contraceptives or in doses that are not specifically tailored for contraception.

The main difference between hormonal therapy and hormonal contraceptives is that hormonal therapy preserves fertility. It is therefore the preferred option for women who are trying to conceive but would also like to control their heavy menstrual bleeding.

Antifibrinolytic Medicine

Antifibrinolytic medicines like Lysteda (tranexamic acid) or Amicar (aminocaproic acid) can help reduce bleeding. Lysteda can reduce your menstrual flow by up to 58%.

The specific function of antifibrinolytic medication is to slow fibrinolysis—a term that refers to the process of breaking down blood clots.

Surgical Treatment

Surgical treatment may be an option for you when you need to have polyps or fibroids removed. Your healthcare provider may also recommend surgery if medication isn't helping you or is contraindicated for any reason. Surgical options include:

  • Operative hysteroscopy: This can be used to remove fibroids or the uterine lining, or to fix problems in your uterus.
  • Endometrial ablation or resection: These procedures remove or destroy all or part of your uterine lining to lessen or stop your periods. They also prevent you from having children.
  • Laparoscopy: This minimally invasive surgery can be used to remove small uterine fibroids and growths with a small surgical incision in your abdomen.
  • Myomectomy: If your fibroids are large, you may need a myomectomy, which involves a larger incision in your abdomen.
  • Hysterectomy: In this surgery, your uterus is removed, which means you won't have periods anymore and you will not be able to conceive. This option is considered when medications haven't helped and/or you are still a long way from menopause.

When to See a Healthcare Provider

  • If your menstrual bleeding is heavy and requires you to change your tampon or pad every couple of hours
  • If the bleeding lasts longer than seven days
  • If blood clots are larger than a quarter
  • If there is an excessive amount of blood clots
  • If you have extreme abdominal pain with nausea or vomiting
  • If you have bleeding or clots while pregnant


Sometimes a heavy flow is simply that—a heavy flow. Other times, it is a symptom of another underlying condition.

In general, blood clots aren't something to worry about. But if you believe you have menorrhagia, your periods are irregular, or you are concerned about painful cramps or other symptoms, go ahead and schedule a visit with your healthcare provider.

You know your body better than anyone else; if something feels off, give your healthcare provider or gynecologist a call.

A Word From Verywell

Unless you are new to having periods, you are probably used to the changes your body goes through during your monthly cycle. Your PMS symptoms and the heaviness of your menstrual flow can vary from month to month, too.

To help you keep track of these changes, you may find it helpful to take notes about your period in a journal or a smartphone app. This information will be useful for your healthcare provider in determining the cause of your heavy period and what kind of treatment is best for you.

Frequently Asked Questions

  • What does a period blood clot look like?

    A menstrual blood clot looks like a dark red blob of blood. Blood clots can vary in size. A normal blood clot is about the size of a dime. Clots that are larger than a quarter are considered very large. If you experience large blood clots during your period, talk to your doctor.

  • Why does my period look like jelly?

    Menstrual blood can be thick—almost like a jelly—on heavy flow days. These jelly-like globs are a mix of blood, tissue, and blood clots released from your uterus. While messy and inconvenient, jelly-like menstrual blood is normal and typically nothing to be concerned about. 

  • What problems can occur from heavy periods?

    Prolonged or heavy menstrual periods are often caused by uterine fibroids, endometriosis, or hormonal imbalances. The main concern with heavy periods is the loss of blood can lead to iron-deficient anemia. 

    Anemia can make you feel tired, dizzy, lightheaded, and weak. Anemia can also cause shortness of breath upon exertion, chest pain, irregular heartbeats, pale or jaundiced skin, cold hands and feet, and tinnitus. 

  • When should I be concerned about blood clots during my period?

    Most women pass blood clots during their monthly period and it typically is not anything to be concerned about. However, if you experience the following, call your doctor:

    • Bleeding lasts longer than seven days
    • Clots larger than a quarter
    • An excessive number of clots
    • Extreme abdominal pain with nausea or vomiting
    • Heavy bleeding that requires you to change your tampon or pad every two hours or less.

    If you are pregnant and experience bleeding or blood clots, call your ob-gyn. 

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