A normal period lasts between 5 and 7 days. If yours has gone beyond that and shows no signs of stopping, something is keeping your uterine lining from shedding cleanly and on schedule. The causes range from harmless hormonal shifts to conditions worth investigating, and most of them are treatable once identified.
What Counts as a Prolonged Period
Bleeding that continues past 7 days is considered prolonged. The typical period produces about 2 to 3 tablespoons of blood total, though it often feels like much more. If you’re consistently losing more than about 5 tablespoons per cycle, or soaking through two or more pads or tampons every hour for two to three consecutive hours, that crosses into heavy bleeding territory and warrants prompt medical attention.
Hormonal Shifts Are the Most Common Cause
Your period depends on a precise hormonal sequence. Estrogen builds the uterine lining, then progesterone stabilizes it. When progesterone drops, the lining sheds in an orderly way. If ovulation doesn’t happen during a cycle (called an anovulatory cycle), progesterone never rises, and estrogen continues building the lining unchecked. When bleeding finally starts, it can be heavier and last longer because there’s simply more lining to shed, and it breaks down unevenly.
This is especially common during two life stages. In the first few years of menstruation, the hormonal system is still maturing, and skipped ovulations are frequent. At the other end, during perimenopause (typically starting in your 40s), estrogen rises and falls unpredictably while progesterone declines. Periods can become longer, shorter, heavier, or more erratic. Both situations are normal transitions, but prolonged bleeding during either one still deserves evaluation if it becomes a pattern.
Thyroid Problems
Your thyroid gland has a direct influence on your menstrual cycle. An underactive thyroid (hypothyroidism) is particularly linked to heavier, longer periods. It disrupts ovulation, which leads to the same estrogen-dominant pattern described above: the lining builds too thick, then sheds irregularly. Hypothyroidism is common enough that it’s one of the first things a doctor will check when periods run long. An overactive thyroid tends to cause the opposite problem, with lighter or less frequent periods.
PCOS
Polycystic ovary syndrome causes chronically irregular ovulation. You might go weeks or months without a period, and when bleeding finally arrives, it can be prolonged and heavy because the lining has been accumulating for much longer than a normal cycle. If your periods are unpredictable in timing and then unusually long when they do show up, PCOS is a likely explanation.
Growths in the Uterus
Physical changes inside the uterus can mechanically interfere with how the lining sheds.
Fibroids are noncancerous muscle growths in the uterine wall. They increase the surface area of the lining, boost blood flow to the uterus, and can compress surrounding blood vessels, causing congestion. They also reduce the uterus’s ability to contract and squeeze blood vessels closed, which is part of how normal bleeding stops. All of this adds up to periods that are heavier and last longer.
Polyps are smaller, finger-like growths on the uterine lining itself. They prevent the lining from shedding completely, so bleeding drags on as the remaining tissue breaks down slowly.
Adenomyosis occurs when tissue that normally lines the uterus grows into the muscular wall. It causes effects similar to fibroids: the thickened muscle compresses the overlying lining, leading to heavier, prolonged bleeding. It’s most common in women in their 30s and 40s and often comes with significant cramping.
Your Birth Control Could Be Responsible
If you recently started or changed a contraceptive method, that’s a strong candidate. Copper IUDs are well known for making periods heavier and longer, particularly in the first few months. In one study, two-thirds of copper IUD users reported increased bleeding in the first nine weeks. By about 12 months, episodes of prolonged bleeding dropped to zero in a small study group, suggesting the body adjusts. However, intermenstrual spotting (bleeding between periods) can actually increase over time with copper IUDs.
Hormonal birth control, including pills, patches, and hormonal IUDs, can cause breakthrough bleeding or extended spotting, especially during the first three months. Missing a pill or taking it at inconsistent times makes this more likely. If you’ve been on hormonal contraception for more than three months and the prolonged bleeding hasn’t resolved, it’s worth discussing with your provider.
Bleeding Disorders
About 13% of women with chronically heavy periods have an underlying bleeding disorder called von Willebrand disease, a condition where the blood doesn’t clot efficiently. Prevalence in individual studies ranges from 5% to 24%. It’s often undiagnosed because heavy periods get normalized, especially if they started in adolescence. Clues that a bleeding disorder might be involved include easy bruising, prolonged bleeding from cuts, bleeding after dental work, or a family history of bleeding problems.
How Prolonged Bleeding Is Evaluated
If your period consistently lasts longer than 7 days, the first step is usually blood work to check for anemia (since prolonged bleeding depletes iron stores) and to measure thyroid function and hormone levels. Iron studies, including ferritin, help determine whether your body’s iron reserves are dropping even if you don’t feel anemic yet.
An ultrasound isn’t always necessary upfront, but it’s useful for spotting fibroids, polyps, or signs of adenomyosis, particularly if initial treatments don’t help. If there’s suspicion of a bleeding disorder based on your history, a referral to a hematologist for specialized testing is the standard approach.
How Prolonged Periods Are Treated
Treatment depends entirely on the cause, which is why getting evaluated matters more than trying to manage it on your own.
For hormonal causes like anovulatory cycles, PCOS, or perimenopause, hormonal treatments can regulate the cycle and thin the lining so it sheds more efficiently. These stabilize estrogen and progesterone levels to restore the normal shedding pattern.
For structural causes like fibroids or polyps, options range from medications that reduce bleeding to procedures that remove the growths. Small polyps can often be removed in an office procedure. Fibroids have a wider range of treatment options depending on their size and location.
There are also non-hormonal medications that help reduce blood loss by supporting the body’s clotting process. These are taken only during the days of your period and can reduce the volume of bleeding, though most studies show they don’t shorten the number of days you bleed.
Thyroid-related prolonged periods typically resolve once thyroid hormone levels are corrected. Bleeding disorders are managed with targeted treatments through a hematologist, often in coordination with a gynecologist.
Signs That Bleeding Needs Urgent Attention
Most prolonged periods are not emergencies, but some situations require same-day care. Soaking through two or more pads or tampons per hour for two to three hours straight is the clearest signal. Other red flags include feeling dizzy or lightheaded when standing, a racing heartbeat, visible paleness, or feeling unusually exhausted. These suggest significant blood loss that may need intervention to stop the bleeding and restore iron levels.