7 Things That Can Cause Heavy Bleeding During Your Period

Underactive and overactive thyroid can be the results of autoimmune disorders (Hashimoto’s disease or Graves’ disease), iodine deficiency, thyroid inflammation (a.k.a. thyroiditis), problems with the pituitary gland (which releases thyroid-stimulating hormone), certain medications, and thyroid tumors.

4. Irregular ovulation

Various hormonal imbalances can cause people to ovulate irregularly. Ovulation releases the hormone progesterone, which keeps the uterine lining from building up, Dr. Schon explains. If a woman isn’t ovulating, there’s nothing to keep that buildup in check. Then, when ovulation does happen (but pregnancy does not), the builtup lining can come out all at once during menstruation, causing heavy bleeding. “Some people can not have a period for six months and then have a period for a month straight,” says Dr. Schon.

One possible cause of these imbalances is polycystic ovary syndrome (PCOS), which affects 5% to 10% of women of childbearing age. If your periods are both heavy and irregular, and you also have excess body hair, hormonal acne, or difficulty getting pregnant, you may want to go to an endocrinologist to get tested for PCOS.

5. Endometrial or cervical cancer

Rarely, a cancerous growth on the uterine lining (endometrium) or cervix can be the cause of heavy bleeding. If you’re over 45 and still have regular periods—but they’re heavy—Dr. Ascher-Walsh says it’s worth getting checked out. Typically, people with cancer have other symptoms, like irregular bleeding, vaginal discharge, pelvic pain, and weight loss, but it’s worth mentioning heavy periods to your doctor so they can look into what’s going on and do any additional testing if they are suspicious.

6. Bleeding disorders

Heavy bleeding during a period could be a sign of a bleeding disorder such as immune thrombocytopenia (ITP), which prevents blood from clotting properly. If you have this condition, you may also bruise more easily than other people and deal with frequent nosebleeds.

A heavy period could also point to the bleeding disorder von Willebrand disease, which leads to abnormal platelets that prevent blood from clotting, especially if the heavy periods started when you first got your period, Dr. Schon says. Von Willebrand disease is the most common inherited bleeding disorder in American women and is seen in between 5% and 24% of women with chronically heavy periods, according to the American Congress of Obstetricians and Gynecologists.

7. Medications

Certain medications can also include heavy bleeding as a side effect. Hormonal birth control, including the pill and IUDs, are usually meant to decrease bleeding—but in some people, Dr. Schon says, they can cause prolonged or heavy bleeding. And the copper IUD, in particular, is associated with more bleeding than other forms of birth control. If you take blood thinners or you’re undergoing chemotherapy, Dr. Schon says your blood may not clot as well, which may also cause a heavier-than-normal flow during your period.

How to deal with heavy bleeding during your period

If your heavy period is bothering you, definitely talk to your doctor. “In gynecology, we think of the period as a vital sign,” says Dr. Schon. “So if it’s changing or abnormal, it’s important to rule out more serious causes.” Most of the time—especially if you haven’t yet reached menopause—whatever is causing your heavy bleeding won’t be super serious, says Dr. Ascher-Walsh.

More good news? There are a lot of effective treatments for heavy periods, ranging from medications to surgical procedures. How your doctor addresses the heavy flow ultimately depends on the cause. For example, if you end up being diagnosed with fibroids, polyps, or other growths, your doctor may recommend a procedure or surgery to remove them. In other cases, treatment could be as simple as starting birth control (or changing the one you’re on, if it’s making you bleed more) to make your periods more predictable and potentially lighter.

Even if you’ve gotten used to your heavy bleeding, don’t blow it off in hopes it’ll go away on its own. “You don’t need to live with a heavy period that can be such a burden every month,” says Dr. Ascher-Walsh. “There are always options.”

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