A period that lasts longer than seven days is considered prolonged, and it’s one of the most common signs of heavy menstrual bleeding. While an occasional longer cycle isn’t always a cause for alarm, consistently bleeding past the seven-day mark usually points to something specific going on in your body, from a hormonal imbalance to a structural change in your uterus. Understanding the most likely causes can help you figure out whether this is a temporary blip or something worth investigating.
What Counts as a Prolonged Period
Normal periods last between two and seven days. Both the CDC and the American College of Obstetricians and Gynecologists define bleeding that extends beyond seven days as heavy menstrual bleeding, clinically called menorrhagia. Duration is just one piece of the picture, though. Other signs that your bleeding is heavier than normal include soaking through a pad or tampon every hour for several hours in a row, needing to double up on pads, waking up at night to change protection, or passing blood clots the size of a quarter or larger.
If you’re only a day or two over seven days once in a while, that may not signal a problem. But if your periods regularly stretch to eight, nine, or ten-plus days, something is driving that pattern.
Hormonal Imbalance Is the Most Common Cause
Your period length depends heavily on the balance between two hormones: estrogen and progesterone. During a normal cycle, estrogen builds up the lining of your uterus in the first half, and progesterone stabilizes it in the second half after ovulation. When you get your period, that lining sheds in an orderly way over a few days.
When those hormones fall out of balance, things go differently. If your body produces too much estrogen relative to progesterone, the uterine lining grows thicker than it should. A thicker lining takes longer to shed, which means more days of bleeding and often heavier flow. This imbalance is especially common during two life stages: the first few years after periods start (adolescence) and the years leading up to menopause (perimenopause), when ovulation becomes less predictable.
Sometimes your ovaries skip ovulation entirely during a cycle, a phenomenon called anovulation. When that happens, your body never produces the progesterone surge that normally keeps the lining in check. The lining continues to thicken under estrogen’s influence, and when it finally breaks down, the result is prolonged, heavy, or irregular bleeding. Anovulatory cycles are a hallmark of polycystic ovary syndrome (PCOS), but they can also happen from stress, significant weight changes, or excessive exercise.
Fibroids and Polyps
Uterine fibroids are noncancerous growths in or on the wall of the uterus. They’re extremely common, particularly in women over 30, and they can distort the uterine cavity in ways that make it harder for the uterus to contract and stop bleeding efficiently. Depending on their size and location, fibroids can turn a five-day period into a week-plus ordeal, often with notably heavier flow.
Uterine polyps are smaller, finger-like growths that develop on the inner lining of the uterus. They’re estrogen-sensitive, meaning they grow in response to estrogen circulating in your body. Polyps can cause irregular bleeding, very heavy flow, or bleeding between periods. Like fibroids, they increase the surface area of tissue that bleeds during your period and can extend its duration.
Thyroid Problems
Your thyroid gland plays a quieter but significant role in regulating your menstrual cycle. An underactive thyroid (hypothyroidism) disrupts the hormonal signaling chain between your brain and your ovaries, which alters estrogen and progesterone levels. The downstream effect on periods can include heavier and longer bleeding. Research has also linked hypothyroidism to reduced levels of certain clotting factors in the blood, which may make it harder for your body to slow menstrual bleeding once it starts.
Thyroid disorders are common enough that they’re one of the first things a doctor will screen for if you report prolonged periods, especially if you also have fatigue, weight changes, or sensitivity to cold.
Bleeding Disorders
Some women bleed longer simply because their blood doesn’t clot as efficiently as it should. Von Willebrand disease is the most common inherited bleeding disorder, affecting roughly 1 in 100 people in the United States. Many women with the condition go undiagnosed for years because they assume their heavy, long periods are just “normal for them.”
Clues that a bleeding disorder might be involved include periods that consistently last longer than seven days, soaking through a pad or tampon every one to two hours on your heaviest days, passing clots larger than a grape, or developing anemia (low red blood cell counts) as a result of menstrual blood loss. If heavy, prolonged periods run in your family, a bleeding disorder is worth exploring.
Your IUD or Other Medications
Copper IUDs are a well-known cause of longer, heavier periods. Unlike hormonal IUDs, the copper device doesn’t thin the uterine lining. Instead, it creates a low-level inflammatory response inside the uterus that can increase both the volume and duration of menstrual bleeding, sometimes significantly.
Hormonal IUDs can also cause prolonged bleeding, but usually only in the first three months after insertion. About 1 in 5 women experience periods lasting longer than eight days during that adjustment window. After three months, the pattern typically reverses: periods get lighter, shorter, and in some cases stop altogether.
Blood thinners (anticoagulants) and certain anti-inflammatory medications can also extend your period by interfering with your body’s ability to form clots and stop bleeding on schedule.
Less Common but Serious Causes
Prolonged bleeding can occasionally point to something that needs prompt attention. Endometrial hyperplasia, a condition where the uterine lining becomes abnormally thick, can cause extended periods and is considered a precursor to endometrial cancer in some cases. Cervical or uterine cancers can also cause prolonged or irregular bleeding, though these are far less common than the other causes listed above, particularly in younger women.
Adenomyosis, a condition where the tissue that normally lines the uterus grows into the muscular wall, is another underdiagnosed culprit. It tends to cause painful, heavy periods that drag on longer than they should, and it’s most common in women in their 30s and 40s.
Tracking What to Share With Your Doctor
If your periods regularly last more than seven days, the most useful thing you can do before a medical visit is track the details. Note how many days you bleed, how often you change your pad or tampon on your heaviest day, whether you pass clots (and roughly how large), and whether you experience any bleeding between periods. A menstrual tracking app works well for this, but a simple calendar note is fine too.
Your doctor will likely start with blood work to check your hormone levels, thyroid function, and iron stores. An ultrasound can reveal fibroids, polyps, or other structural changes. If a bleeding disorder is suspected, specific clotting tests can identify conditions like von Willebrand disease. The cause of prolonged periods is almost always identifiable, and most causes are highly treatable once diagnosed.