Overview

Heavy menstrual bleeding is blood loss that happens with periods that is very heavy or lasts for several days. It can be concerning to bleed a lot during periods. But most women don't have enough blood loss for it to be classified as heavy menstrual bleeding. This condition used to be called menorrhagia.

Some women have other unusual bleeding related to their periods. This could include bleeding that happens between periods or bleeding that happens earlier or later in their cycles than expected. This type of bleeding is called abnormal uterine bleeding or irregular menstrual bleeding.

With heavy menstrual bleeding, blood flow and cramping make it harder to do your usual activities. If you dread your period because you have heavy menstrual bleeding, talk with your doctor or other healthcare professional. There are many treatments that can help.

Symptoms

Symptoms of heavy menstrual bleeding may include:

  • Soaking through one or more sanitary pads or tampons every hour for several hours in a row.
  • Needing double sanitary protection to control your menstrual flow.
  • Getting up at night to change sanitary pads or tampons.
  • Bleeding for more than a week.
  • Passing blood clots larger than a quarter.
  • Limiting daily activities due to heavy menstrual flow.
  • Feeling tired, fatigued or short of breath as the result of blood loss.

When to see a doctor

Seek medical help before your next scheduled exam if you have:

  • Vaginal bleeding so heavy it soaks at least one pad or tampon an hour for more than two hours in a row.
  • Bleeding between periods or unusual vaginal bleeding.
  • Vaginal bleeding after menopause.

Causes

In some cases, the reason for heavy menstrual bleeding is unknown. But a number of conditions may cause heavy menstrual bleeding. They include:

  • Hormones being out of balance. In a typical menstrual cycle, there's a balance between the hormones estrogen and progesterone. This controls the buildup of the lining of the uterus. The lining of the uterus also is known as the endometrium. This lining is shed during a menstrual period. When hormones are out of balance, the lining becomes too thick and sheds by way of heavy menstrual bleeding or unexpected bleeding between periods.

    A number of conditions can cause hormone imbalances. These include obesity, insulin resistance, thyroid problems and polyendocrine metabolic ovarian syndrome, which also is called PMOS.

  • Problems with the ovaries. Sometimes ovaries don't release an egg during a menstrual cycle. This also is known as anovulation. When this happens, the body doesn't make the hormone progesterone the way it usually does during a menstrual cycle. This leads to hormone imbalance and may result in heavy menstrual bleeding or unexpected bleeding between periods.
  • Uterine fibroids. These tumors develop during childbearing years. They are benign, which means they are not cancer. Uterine fibroids may cause heavier than normal menstrual bleeding or bleeding that goes on for a long time.
  • Polyps. These small growths on the lining of the uterus may cause menstrual bleeding that is heavy or lasts for a long time. They may cause bleeding between periods. Polyps also can cause spotting or bleeding after menopause. These growths are not cancer.
  • Adenomyosis. In this condition, glands from the lining of the uterus grow into the wall of the uterus itself. This can cause heavy bleeding and painful periods.
  • Intrauterine device, also called an IUD. Heavy menstrual bleeding is a well-known side effect of using a hormone-free IUD for birth control. Talk to your healthcare professional about other birth control options. IUDs with progestin may ease heavy menstrual bleeding.
  • Pregnancy complications. Having a late period that's very heavy may be due to a miscarriage. Another cause of heavy bleeding during pregnancy includes the unusual location of the placenta, which supplies nutrition to the baby and removes waste. The placenta may be too low or cover the opening of the uterus, which is called the cervix. This condition is known as placenta previa.
  • Cancer. Cancer of the uterus or cervix can cause abnormal uterine bleeding, unexpected or heavy menstrual bleeding. These cancers can happen before or after menopause. Women who have had an abnormal Pap test in the past are at higher risk of cervical cancer.
  • Genetic bleeding disorders. Some bleeding disorders that run in families cause heavy menstrual bleeding. These include von Willebrand's disease, a condition in which the blood does not clot properly.
  • Medicines. Some medicines can result in heavy or lengthy menstrual bleeding. These include hormone medicines such as birth control pills that have estrogen and progestin. These medicines typically help lessen menstrual bleeding but sometimes cause unexpected bleeding between periods. Medicines that prevent blood clots also may cause heavy menstrual bleeding. They include warfarin (Jantoven), enoxaparin (Lovenox), apixaban (Eliquis) and rivaroxaban (Xarelto).
  • Other medical conditions. Liver, kidney and thyroid disease also may cause heavy menstrual bleeding.

Risk factors

Risk factors vary with age and the medical conditions you have. Usually, the release of an egg from the ovaries signals the body to make progesterone. Progesterone is the hormone most responsible for keeping periods regular. If no egg is released, the body does not make enough progesterone. This can result in heavy menstrual bleeding or unexpected bleeding between periods.

In teenagers, an irregular period or heavy menstrual bleeding often happens when an egg is not released during a monthly cycle. Teenagers are most likely to have cycles without an egg release during the first year after they have their first period.

In older women of reproductive age, heavy menstrual bleeding is often caused by problems with the uterus. These include fibroids, polyps and adenomyosis. But other problems also could cause heavy menstrual bleeding. Examples include cancer of the uterus, bleeding disorders, side effects of medicines, and liver or kidney disease.

Complications

Menstrual bleeding that is too heavy or lasts too long can lead to other medical conditions. These include:

  • Anemia. Heavy menstrual bleeding can cause anemia related to blood loss. Anemia is a condition in which the body does not have enough healthy red blood cells or hemoglobin to carry oxygen to the body's tissues. Hemoglobin is a protein found in red blood cells that carries oxygen from the lungs to all other organs in the body.

    Iron deficiency anemia occurs as the body tries to make up for lost red blood cells. The body uses iron stores to make more hemoglobin so that enough oxygen can be carried to tissues. Heavy menstrual bleeding may make iron levels too low. This may result in iron deficiency anemia.

    Symptoms include headaches and feeling tired. Although diet plays a role in iron deficiency anemia, the problem is made worse by heavy menstrual periods.

  • Severe pain. Along with heavy menstrual bleeding, you might have painful menstrual cramps. This also is known as dysmenorrhea. Talk to your healthcare professional if your cramps make it hard to do your daily activities.
By Mayo Clinic Staff