What Causes Large Blood Clots During Your Period?

Passing blood clots during the menstrual cycle can be normal, especially when you are going on your heaviest days of period. However, getting heavy bleeding with large clots can be an indication of some serious problems.

There can be numerous possible reasons and causes that your period is getting heavier with abnormal period blood clots, and the good news is that these causes and problems can be treatable.

Hormones like oestrogen and progesterone, which control the formation of the uterine lining, should be in balance. However, due to imbalance between these hormones, the uterine lining gets developed in excess, resulting in heavy bleeding.

Know the causes of experiencing heavier-than-normal periods with large blood clots:

Thyroid Conditions:

The thyroid gland is responsible for hormone production and distribution. It can cause havoc on your cycle if it's not working properly. Hypothyroidism and hyperthyroidism are the thyroid disorders that can impact the flow and severity of your menstrual cycle.

Polyps and Fibroids:

Fibroids can settle in the uterus, making your period heavier and longer than usual. Heavy clotting can also be caused by uterine polyps that form on the cervix or in the uterine lining. Uterine obstruction like fibroid can also be the reason behind excessive bleeding, huge blood clots, stomach cramps or lower back and body pain during your menstrual period.

Birth Control:

Birth control methods can be a significant cause of passing large menstrual blood clot during periods. Non-hormonal IUDs might cause irregular periods and blood clots. Consult a doctor if you have an IUD and are having a lot of clotting and bleeding.


Many over-the-counter and prescription medications can contribute to clot-filled periods. Anti-inflammatory and hormonal medications and anticoagulants can all cause irregular bleeding with clots and menstrual flow. If you're having trouble passing large period blood clots during your periods, consult the doctor for the medications and any potential adverse effects.


A miscarriage or ectopic pregnancy (when a fetus begins to form outside of the uterus) can oftentimes be confused for a heavy period blood clot. The pregnancy loss might sometimes result in large menstrual blood clot


In this condition, tissues that grow inside the uterus expand outside of it. You may experience excessive clotting and bleeding, with abdominal pain and body cramps.

Polycystic Ovarian Syndrome (PCOS):

Another disorder that can cause excessive clots and bleeding throughout your cycle is a PCOS. Follicles grow on the ovaries and prevent eggs from being produced on a regular basis, causing irregular menstruation periods.

Other Chronic Conditions

Thyroid problems, adenomyosis, blood diseases like Von Willebrand disease, certain types of malignancies, and Pelvic Inflammatory Disease are some of the common chronic conditions that might make your period blood clot heavier than it should be.

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