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Having a heavy menstrual flow now and then is common, but if it’s extremely heavy, it may be a sign of a hormonal imbalance or other condition.
8 most common causes
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Most common questions
What is a heavy menstrual flow?
A heavy menstrual flow is very common, affecting an estimated 27-54% of women. Heavy menstrual bleeding is when your periods are extremely heavy, meaning they last longer than 7 days or you lose more blood (80 milliliters) than is typical during menstruation (35-40 milliliters).
Or, more simply, it can be defined as a menstrual flow so heavy that it affects your quality of life. Heavy menstrual bleeding can also lead to other problems like anemia and severe pain.
The main causes of a heavy period are hormone imbalances, irregular ovulation, and uterine fibroids or polyps, adenomyosis, and pregnancy complications. In adolescent girls, a heavy flow is usually from hormonal imbalances or irregular ovulation. In adult women, it’s more likely caused by fibroids, adenomyosis, and polyps.
It is not normal to have to miss school, work or activities because your flow is so heavy that you need to constantly change your pad or tampon, or it leaks through your clothing. —Dr. Jessica Katz
What it feels like
A heavy menstrual flow can be very uncomfortable, causing pelvic pain and cramps that may make you miss work, school, or activities. You may find yourself changing your pad or tampon more frequently (as often as 1–2 hours), waking up during the night to change it, or using more than one type of sanitary product at a time.
If your flow is heavy every month, or you have an unusually heavy menstrual cycle, you may lose enough blood to cause low blood pressure or iron-deficiency anemia. These conditions cause symptoms such as:
- Shortness of breath
- Lightheadedness and dizziness
- Passing blood clots with your menstrual flow, which can be as large as golf balls
If you have a heavy menstrual flow regularly, see your doctor to discuss potential causes and how to treat it.
No matter what’s causing a heavy period, you should go to the ER if you’re soaking through a highly absorbent pad or tampon every 1–2 hours for several hours or you have symptoms of low blood pressure or anemia.
It’s possible that you’ll need to be admitted to the hospital to slow the flow. This could mean having a surgical procedure—most commonly a dilation and curettage (D&C). During this procedure, tissue is removed from the uterus. Or you may be given high doses of medications like birth control, estrogen, or progesterone to slow the bleeding.
Anovulation is when the ovaries don’t release an egg during the menstrual cycle. It is from changes in hormone levels and can cause irregular, prolonged, and often a heavy period. Anovulatory bleeding is more common in teenagers and in women who are perimenopausal, obese, or extremely thin.
Causes of anovulation include polycystic ovary syndrome, hyperprolactinemia, anorexia, excessive exercise, stress, thyroid disorders, premature ovarian failure, and certain medications.
Common: Anovulation leading to heavy menstrual bleeding happens in 3–18% of menstruating women [Source: National Institutes of Health].
- Spotting throughout the month
- Periods that are shorter or last longer than usual
Treatment and urgency: If heavy bleeding is causing symptoms like dizziness, lightheadedness, fainting, or headache, it’s important to see a doctor right away because the bleeding might need to be stopped by medication or surgery.
Anovulation is treated with medication to increase hormone levels and treating the conditions that may be causing it. Lifestyle changes like maintaining a healthy weight and reducing stress may also help regulate your menstrual cycle.
Fibroids are noncancerous tumors that develop in or around the uterus. They can put pressure on the uterine wall and prevent the uterus from contracting properly. They can also cause higher levels of hormones and the growth of blood vessels—all contributing to heavier periods.
Very common: About 70% of women have fibroids [Source: BJOG: an International Journal of Obstetrics & Gynaecology].
- Longer or more frequent periods
- Bleeding between periods
- Anemia due to blood loss
- Pelvic pain or cramping
- Increased abdominal/pelvic girth
- Painful intercourse
- Bladder or bowel pressure
- Urinary or bowel issues
Treatment and urgency: Fibroids are usually treated with medication, like birth control pills and gonadotropin-releasing hormone (GnRH) agonists, or surgical procedures including:
- Uterine ablation (destroying a thin layer of the lining of the uterus)
- Myomectomy (removing fibroids)
- Hysterectomy (removing the uterus)
3. Endometrial and cervical polyps
Both endometrial polyps and cervical polyps are growths that can make your period heavy. Endometrial polyps grow on the inner wall of the uterus, while cervical polyps are found on the surface of the cervix. These growths are not usually cancerous.
Common: About 8–9% of women have endometrial polyps. Cervical polyps are less common, affecting 2–5% of women [Source: Obstetrics & Gynecology Science; National Institutes of Health].
- Frequent, unpredictable periods
- Bleeding between periods
Treatment and urgency: Make an appointment with your doctor. Most commonly, doctors find and remove polyps during a procedure called a hysteroscopy, in which a thin tube is inserted into the vagina.
Adenomyosis is when the tissue that lines the inside of the uterine wall grows into the outer muscular layer of the uterus. This causes the uterus to thicken and enlarge, which can lead to heavy menstrual bleeding. Adenomyosis is more common in women between the ages of 35–50 who have endometriosis, uterine fibroids, or have had at least one pregnancy.
Common: Adenomyosis affects 20–35% of women [Source: National Institutes of Health].
- Severe cramping
- Uterine enlargement
- Pain during intercourse
- Large blood clots
- Chronic pelvic pain
- Tenderness or pressure in your lower abdomen
Treatment and urgency: Adenomyosis can be treated by your doctor. Treatments include anti-inflammatory drugs and birth control pills or devices. In severe cases, your doctor may recommend a hysterectomy.
5. Blood clotting disorders
Certain inherited bleeding disorders prevent your blood from clotting when you’re injured and can make menstrual flow heavier. The most common type of these disorders is von Willebrand disease. Other examples include hemophilia and thrombocytopenia.
Common: As many as 1 in 10 women with heavy menstrual periods have a bleeding disorder (U.S. Department of Health & Human Services].
- Large bruises from a minor bump or injury
- Nosebleeds that are difficult to stop or happen regularly
- Heavy vaginal bleeding from conditions like endometriosis
- Blood in stool or urine
- Bleeding excessively after an injury, surgery, or getting dental work
Treatment and urgency: While there are no cures for bleeding disorders, there are medications that help control them. These include birth control, iron supplements, hormones (desmopressin), antifibrinolytics, and clotting factors.
inding an underlying bleeding disorder in people with extremely heavy periods without any anatomical abnormalities, like polyps or fibroids, isn’t uncommon. There are benefits of knowing if you have a bleeding disorder, so it is important to rule it out. —Dr. Katz
6. Non-hormonal IUD
Heavier menstrual flow is one of the main side effects of a non-hormonal form of birth control called the Paragard IUD.
Common: 67% of women using Paragard complained of menstrual side effects during the first year of use [Source: Contraception].
- Back pain
- IUD expulsion
- Prolonged bleeding
Treatment and urgency: Your doctor can prescribe a short course of birth control pills or progesterone to lessen the bleeding or you may want to have the device removed.
7. Miscarriage or ectopic pregnancy
Even if you’re on birth control, there is a chance you may be pregnant and are having a miscarriage or have an ectopic pregnancy (when the fertilized egg attaches outside of the uterus, usually the fallopian tubes.) Both conditions cause heavy bleeding.
Common: As many as 25% of all pregnancies end in miscarriage. Ectopic pregnancy occurs in 1–2% of all pregnancies [Sources: National Institutes of Health; Fertility Research & Practice].
- Pelvic pain
- Signs of pregnancy, such as nausea, vomiting, and breast tenderness
Treatment and urgency: An ectopic pregnancy is a life-threatening complication, especially if the fallopian tube has ruptured. If it’s caught early and the tube is intact, an ectopic pregnancy can be treated with a medication called methotrexate. Otherwise, surgery is needed to remove the pregnancy and, if necessary, the ruptured fallopian tube.
Call your doctor if you think you are having a miscarriage.
Treatment of heavy menstrual flow depends on what’s causing it. A common treatment is taking birth control pills. If you are not planning on having children in the future, your doctor may discuss surgical procedures like endometrial ablation or hysterectomy. If you want to have children or are not sure, less invasive procedures like myomectomy for fibroids or polypectomy for polyps are alternative options.
People may think it is easy to guess the amount of blood you lose during your period. Most people either overestimate or underestimate the amount of blood they lose each month. —Dr. Katz
Why is my period suddenly heavy this month?
It’s common for a cycle to be heavier than usual now and then. But if it seems very different from how it usually is, you may want to call your doctor to rule out any underlying causes. If you are sexually active, take a pregnancy test, since a miscarriage or ectopic pregnancy can lead to heavy bleeding and pain and be life-threatening.
Another reason for your period to suddenly be heavier is if you started, switched, or stopped birth control. Taking a blood thinner, even aspirin or ibuprofen, may cause a heavier period. Infections of the uterus, including sexually transmitted infections (gonorrhea, chlamydia), can also cause an abnormally heavy menstrual flow.
Why do I have a heavy period with clots?
Most women pass clots during their period at some point, which is considered normal. Clots are more common with heavy periods. You might also have pain when your cervix widens to pass the clot. Call your doctor if you have a heavy menstrual flow with large, golf ball–sized clots. It may be a sign of thyroid disease, uterine polyps or fibroids, a bleeding disorder, or uterine or cervical cancer.
Why did my period get heavy after I turned 40?
The years leading up to menopause (the end of your menstrual cycles) is called perimenopause. The average age of menopause is 51, so most women will experience perimenopause in their 40s. On average, this phase lasts 4 years.
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