Heavy Menstrual Bleeding: How Much Is Too Much?

How much bleeding is too much?

Most people lose about 30 to 40 ml (2 to 3 tablespoons) of blood per period. Research defines heavy bleeding as more than 80 ml per cycle, but nobody measures that at home. Doctors now use a practical definition: bleeding that interferes with your life. These are signs your periods are heavy:

• soaking through a pad or tampon every 1 to 2 hours
• needing a pad and tampon together, or a menstrual cup emptied every 2 hours or less
• waking at night to change protection, or bleeding through onto sheets
• passing clots larger than a quarter (about 2.5 cm or 1 inch)
• avoiding activities, work or school because of bleeding
• feeling tired or breathless during or after periods

Heavy bleeding is about volume. Periods that last longer than 7 or 8 days are covered under long menstrual periods, though the two often go together.

What causes heavy periods

Problems in the uterus

• Uterine fibroids: non-cancerous muscle growths, very common in the 30s and 40s and in Black women. Fibroids inside or bulging into the cavity cause the heaviest bleeding.
• Adenomyosis: lining tissue growing into the muscle wall, causing heavy, painful periods and a bulky uterus, often after childbirth.
• Endometrial polyps: overgrowths of the lining.
• Endometrial hyperplasia and cancer: less common, more likely over 45, with obesity or with irregular bleeding.

Hormonal causes

• Cycles without ovulation: in the teen years, perimenopause and polycystic ovary syndrome, the lining builds up without the progesterone that normally limits it, then sheds heavily.
• Hypothyroidism: an underactive thyroid can make periods heavier.

Bleeding disorders

Von Willebrand disease is the most common inherited bleeding disorder and is found in a notable share of people with heavy periods. Suspect it if periods have been heavy since your first one, or with frequent nosebleeds, bleeding gums, easy bruising, or heavy bleeding after dental work, surgery or childbirth. Low platelets and other clotting disorders are less common causes.

Medicines and devices

• copper IUD, especially in the first year
• blood thinners such as warfarin, apixaban and rivaroxaban
• sometimes some antidepressants (SSRIs) and herbal supplements that affect clotting

Often no cause is found

In many people with heavy periods, tests are normal. This is thought to come from changes in how the lining controls bleeding locally. It responds well to treatment.

Heavy bleeding and anemia

Heavy periods are the commonest cause of iron deficiency in women of reproductive age. Symptoms of iron deficiency anemia include tiredness, breathlessness on exertion, headaches, a fast heartbeat, pale skin, brittle nails, hair loss, restless legs and cravings for ice. Low iron stores (ferritin) can cause tiredness even before anemia develops.

How heavy menstrual bleeding is diagnosed

A doctor will ask about the pattern and impact of your periods, clots, pain, contraception, pregnancy plans and bleeding symptoms in you and your family. Expect:

• a complete blood count and usually ferritin
• a pregnancy test if relevant
• thyroid tests if you have other symptoms
• clotting tests and von Willebrand studies if heavy periods began at your first period or you have other bleeding symptoms
• a pelvic exam and transvaginal ultrasound to look for fibroids, polyps and adenomyosis
• hysteroscopy or endometrial biopsy in people over 45, with risk factors, or when treatment does not work

Treatment

Non-hormonal medicines (taken only during your period)

• Tranexamic acid: reduces blood loss by roughly a third to a half. It is taken only on heavy days. It is not suitable for people with a history of blood clots.
• NSAIDs such as ibuprofen, naproxen or mefenamic acid: reduce bleeding by about a quarter and ease cramps. Follow the label dose.

Hormonal treatments

• Levonorgestrel IUD (hormonal coil): the most effective medical treatment. It reduces blood loss by about 70 to 90 percent in most users, and many stop bleeding altogether. It lasts several years and is reversible.
• Combined hormonal contraception (pill, patch or ring): lighter, regular periods, and can be taken continuously to skip periods.
• Progestin-only pills or injections.
• GnRH-based medicines for fibroid-related bleeding, used under specialist care.

Iron

Iron tablets or, if needed, IV iron to restore iron stores. Take iron with vitamin C and away from tea, coffee and calcium.

Procedures and surgery

• Hysteroscopic removal of polyps and fibroids inside the cavity.
• Uterine artery embolization or myomectomy for larger fibroids.
• Endometrial ablation: destroys the lining; for people who do not want future pregnancy.
• Hysterectomy: a permanent cure, considered when other treatments have failed.

Frequently asked questions

How do I know if my period is too heavy?

Your period is likely too heavy if you soak through a pad or tampon every 1 to 2 hours, need to double up, wake at night to change, pass clots larger than a quarter, bleed longer than 7 days, or feel tired and breathless. If it disrupts your life, it counts as heavy.

What is the most common cause of heavy menstrual bleeding?

Fibroids are one of the most common identifiable causes, followed by adenomyosis, polyps and hormonal imbalance around the teen years and perimenopause. Bleeding disorders are an under-recognized cause. In many people, no structural cause is found.

When should I go to the ER for heavy period bleeding?

Go to the ER if you soak through a pad or tampon every hour for 2 hours or more, or have dizziness, fainting, a racing heart, chest pain or shortness of breath. Also go if you could be pregnant and have heavy bleeding with pain.

What is the best treatment for heavy periods?

The hormonal IUD is the most effective medical treatment for most people. Tranexamic acid works well if you prefer a non-hormonal option taken only on heavy days. The best choice depends on the cause, your pregnancy plans, and your preferences.

Can heavy periods cause anemia?

Yes. Heavy periods are the leading cause of iron deficiency anemia in women of reproductive age. Tiredness, breathlessness, pale skin and hair thinning are common signs. A blood count and ferritin test check for it, and iron supplements treat it.