Heavy periods (called menorrhagia) mean menstrual bleeding that is unusually heavy or lasts longer than about 7 days. The most common heavy periods causes include uterine fibroids or polyps, hormone imbalances such as PCOS, certain IUDs, and bleeding disorders. Effective treatments exist, so it is worth talking to a healthcare provider.
What counts as a heavy period?
Menstrual flow varies a lot from person to person, so "heavy" is defined by its effect on you rather than an exact measurement. According to the CDC and the NHS, signs of heavy menstrual bleeding include:
- Soaking through one or more pads or tampons every hour for several hours
- Needing to change protection during the night
- Doubling up on pads, or using both a pad and a tampon
- Passing blood clots larger than a coin (around 2.5 cm)
- Bleeding for more than 7 days
- Symptoms of anemia, such as tiredness, weakness, or shortness of breath
If your periods regularly disrupt work, sleep, or daily activities, that alone is a good reason to seek advice — heavy bleeding is common and treatable.
Common causes of heavy periods
Heavy bleeding can have many causes, and in some cases a provider may not find a specific reason. The categories below cover most cases.
Growths in the uterus
Non-cancerous growths are among the most frequent causes. Fibroids (muscular growths in the wall of the uterus) and polyps (small growths on the uterine lining) can both increase bleeding. Adenomyosis, where uterine-lining tissue grows into the muscle wall, can also cause heavier, more painful periods.
Hormonal imbalances
Your menstrual cycle is driven by a balance of estrogen and progesterone. When ovulation does not happen regularly, the lining can build up and shed unevenly, causing heavier bleeding. Conditions linked to this include PCOS and thyroid problems. This is also why heavy or irregular periods are more common in the years after your first period and as you approach menopause.
Bleeding and clotting disorders
Inherited conditions such as von Willebrand disease, or low platelets, can make it harder for blood to clot — leading to heavier periods, sometimes from the very first cycle. Blood-thinning medications (anticoagulants) and aspirin can have a similar effect.
Other causes
- Certain IUDs — non-hormonal (copper) IUDs can increase flow, especially in the first months
- Pregnancy complications, including miscarriage or ectopic pregnancy
- Pelvic infection or, rarely, cancer of the uterus or cervix
- Endometriosis — see our overview of endometriosis
Why heavy periods are worth treating
Beyond the daily disruption, ongoing heavy bleeding can lower your iron stores and lead to iron-deficiency anemia. The CDC notes this can leave you feeling tired or weak and may affect overall health. A simple blood test can check your iron and rule out anemia, so do not dismiss persistent fatigue as "just my period."
How heavy periods are diagnosed
To find the cause, a provider may ask about your cycle and review your symptoms, then use one or more of the following, as described by ACOG:
- A pelvic exam and your medical history
- Blood tests to check for anemia, thyroid issues, or clotting problems
- An ultrasound to look at the uterus and ovaries
- Sometimes a biopsy of the uterine lining or a closer look inside the uterus (hysteroscopy)
Tracking your bleeding beforehand helps. Our guide on how to track your menstrual cycle can make that conversation more productive.
Treatment options
Treatment depends on the cause, your symptoms, and whether you want to become pregnant in the future. Options generally fall into three groups.
Medications
- Tranexamic acid — a non-hormonal medicine taken during your period to reduce bleeding
- NSAIDs such as ibuprofen — can lessen flow and ease period pain
- Iron supplements — to treat or prevent anemia
Hormonal options
- The hormonal IUD (IUS) — often a first-line option that thins the lining and reduces bleeding
- Combined or progestogen-only pills — to regulate and lighten periods
Procedures
When medication is not enough, or for specific causes like fibroids, a provider may discuss endometrial ablation, fibroid removal, or — as a last resort — hysterectomy.
When to see a healthcare provider
Make an appointment if you:
- Soak through a pad or tampon every hour or two
- Bleed for longer than 7 days or pass large clots
- Feel tired, dizzy, or short of breath
- Have bleeding between periods or after sex — see spotting between periods
- Notice your periods have suddenly become much heavier
Seek urgent care for very heavy bleeding accompanied by weakness, fainting, or a fast heartbeat.
The bottom line
Heavy periods are common, and the heavy periods causes most often come down to fibroids or polyps, hormone imbalances, bleeding disorders, or certain medications — though sometimes no cause is found. The good news is that effective treatments exist, from simple medications to hormonal options and procedures. Because heavy bleeding can lead to anemia and may signal an underlying condition, it is worth talking with a healthcare provider rather than putting up with it. For more on menstrual health, visit our reproductive and menstrual health hub.
