A normal period lasts about 4 to 5 days. If yours regularly stretches past 7 days, it’s considered prolonged, and there’s usually an identifiable reason behind it. The causes range from hormonal shifts and structural changes in the uterus to thyroid problems and bleeding disorders, and most are treatable once identified.
You’re far from alone in dealing with this. Depending on how it’s measured, somewhere between 10% and 65% of women report heavy or prolonged menstrual bleeding at some point in their lives, with the highest rates among women in their 40s and early 50s.
Hormonal Imbalances That Extend Bleeding
Your period length is controlled by a carefully timed hormonal sequence. After you ovulate, your body produces progesterone, which stabilizes the uterine lining and eventually triggers a clean, predictable shed. When ovulation doesn’t happen (or happens irregularly), progesterone stays low, and the lining keeps building without that stabilizing signal. The result is uneven, drawn-out bleeding as the thickened lining sheds in patches rather than all at once.
This is one of the most common reasons for long periods, and it can happen to anyone. Stress, significant weight changes, and intense exercise can all disrupt ovulation. Polycystic ovary syndrome (PCOS) is another frequent culprit, since it causes irregular or absent ovulation as a core feature of the condition.
How Thyroid Problems Affect Your Period
An underactive thyroid (hypothyroidism) can quietly extend your periods through a chain reaction of hormonal disruption. Low thyroid hormone suppresses a key brain signal called gonadotropin-releasing hormone, which your ovaries need to function properly. At the same time, the body compensates by raising levels of another hormone, prolactin, which interferes with estrogen production and throws off your cycle’s regularity.
There’s also a direct effect on bleeding itself. Low thyroid hormone changes how your blood clots, potentially leading to heavier flow. It can also cause the uterine lining to thicken excessively and shed unpredictably. If your long periods come with fatigue, weight gain, dry skin, or feeling cold all the time, a simple blood test can check your thyroid function.
Fibroids, Polyps, and Adenomyosis
Structural growths in or on the uterus are a physical reason periods drag on. Uterine fibroids are noncancerous muscle growths that can distort the uterine wall, increase the surface area of the lining, and interfere with the uterus’s ability to contract and stop bleeding efficiently. They’re extremely common, particularly after age 30.
Uterine polyps are softer, finger-like growths that form when cells in the uterine lining overgrow. They’re estrogen-sensitive, meaning they grow in response to estrogen in the body. Polyps cause irregular bleeding, very heavy flow, and bleeding between periods. Both fibroids and polyps are typically found on ultrasound.
Adenomyosis is a condition where tissue that normally lines the uterus grows into the muscular wall instead. This causes the uterus to enlarge and can lead to heavy, prolonged periods along with significant cramping. Adenomyosis often coexists with fibroids and endometriosis, which can make it harder to pin down through symptoms alone.
Bleeding Disorders You Might Not Know About
Some women bleed longer simply because their blood doesn’t clot as efficiently. Von Willebrand disease is the most common inherited bleeding disorder, and heavy periods are often its most noticeable symptom. Many women with this condition go years without a diagnosis because they assume their periods are just “bad.”
A bleeding disorder is more likely if your periods have been heavy since your very first one. Other clues include a history of excessive bleeding after dental work or surgery, frequent nosebleeds (once or twice a month), gums that bleed easily, or a family history of bleeding problems. If two or more of those apply alongside long, heavy periods, testing for von Willebrand disease and related clotting conditions is worth pursuing.
Perimenopause and Changing Cycles
If you’re in your late 30s to early 50s and your periods have recently started lasting longer, perimenopause is a likely explanation. During this transition, estrogen and progesterone rise and fall unpredictably rather than following their usual monthly pattern. Ovulation becomes irregular, and without consistent ovulation, you lose the progesterone signal that keeps bleeding controlled.
Periods during perimenopause can be longer, shorter, heavier, lighter, or skipped entirely, sometimes cycling through all of these patterns over several months. This phase typically lasts 4 to 8 years before menopause. The unpredictability can be frustrating, but it’s a normal part of the hormonal transition. That said, new heavy or prolonged bleeding during perimenopause still deserves evaluation, since fibroids and polyps also become more common in this age range.
When Long Periods Cause Anemia
The biggest day-to-day health risk of prolonged bleeding is iron deficiency anemia. Every period costs you iron, and when bleeding lasts beyond a week (or is heavy throughout), your body may not be able to replace what it loses before the next cycle starts.
Signs of anemia from heavy periods include extreme tiredness, weakness, pale skin, shortness of breath with normal activities, dizziness, cold hands and feet, and brittle nails. Some people develop unusual cravings for ice, dirt, or non-food items, which is a well-documented symptom of iron deficiency. If you’re soaking through a pad or tampon every two hours, passing clots larger than a quarter, or feeling winded doing things that used to be easy, your iron levels may be dropping.
How Prolonged Periods Are Evaluated
A doctor will typically start with blood work to check your iron levels, thyroid function, and hormone levels. A transvaginal ultrasound is usually the first imaging step, since it can reveal fibroids, polyps, and signs of adenomyosis without any invasive procedure.
If the ultrasound doesn’t explain the bleeding, or if there are risk factors for more serious conditions, an endometrial biopsy may follow. This involves taking a small tissue sample from the uterine lining to check for abnormal cell growth. For bleeding that persists despite initial testing and treatment, a more detailed look inside the uterus with a camera (hysteroscopy) can identify problems that standard ultrasound misses.
Treatment Options That Shorten Bleeding
Treatment depends on the cause, but several options can reduce both the duration and volume of bleeding. Hormonal birth control (pills, hormonal IUDs, or injections) works by regulating or thinning the uterine lining, which shortens periods and lightens flow. A hormonal IUD is one of the most effective options, often reducing bleeding dramatically within a few months.
For women who prefer non-hormonal treatment, tranexamic acid is a medication taken only during your period that helps blood clot more effectively. In clinical studies, it reduced menstrual blood loss by 40 to 65%, and it worked better than anti-inflammatory painkillers or certain hormonal alternatives. Anti-inflammatory medications like ibuprofen can also modestly reduce flow and help with cramping.
When fibroids or polyps are the cause, removing them often resolves the prolonged bleeding directly. Procedures range from minimally invasive options done through the cervix to more involved surgeries depending on the size and location of the growths. For adenomyosis that doesn’t respond to medication, more targeted treatments may be recommended.