A normal period lasts about four to five days, with most people losing only two to three tablespoons of blood total. If your period regularly stretches past seven days, it’s considered prolonged, and there’s usually an identifiable reason behind it. The causes range from simple hormonal shifts to structural changes in the uterus, and most are treatable once you know what’s going on.
Hormonal Imbalances
Your period ends when your body’s hormonal signals tell the uterine lining to stop shedding and start rebuilding. When those signals are off, bleeding can drag on. The two hormones that orchestrate your cycle, estrogen and progesterone, need to rise and fall in a specific pattern. If progesterone drops too early, stays too low, or estrogen stays elevated for too long, the lining doesn’t shed cleanly, and you bleed for extra days.
Polycystic ovary syndrome (PCOS) is one of the most common reasons for this kind of disruption. With PCOS, ovulation doesn’t happen reliably, which means progesterone levels stay low. The uterine lining keeps thickening under estrogen’s influence until it eventually breaks down unevenly, producing a period that’s both heavier and longer than normal. Thyroid problems can cause similar issues. An underactive thyroid slows the hormonal signaling that regulates your cycle, often leading to prolonged or unusually heavy bleeding.
Uterine Fibroids and Polyps
Fibroids are noncancerous growths in the muscular wall of the uterus. They’re extremely common, and depending on their size and location, they can physically interfere with the uterus’s ability to contract and stop bleeding. The uterus squeezes down after shedding its lining (similar to how it contracts during labor), and fibroids can prevent those contractions from compressing blood vessels shut.
Polyps are a different type of growth. They form from an overgrowth of the uterine lining itself and attach to the inner wall by a base or thin stalk. They’re estrogen-sensitive, meaning they grow in response to estrogen circulating in your body. Polyps cause irregular bleeding, very heavy flow, and spotting between periods. Both fibroids and polyps are detectable on ultrasound and are usually treatable with minor procedures.
Adenomyosis
Adenomyosis happens when tissue that normally lines the inside of the uterus grows into the muscular wall instead. Each month, that embedded tissue still responds to your hormones, swelling and breaking down just like the regular lining. But because it’s trapped within the muscle, it causes the uterus to enlarge and produces periods that last longer than usual, with significantly more pain and heavier flow. It’s often confused with endometriosis, but the key difference is location: endometriosis involves tissue growing outside the uterus, while adenomyosis is confined to the uterine wall itself. Diagnosis typically requires a transvaginal ultrasound or MRI, which can show characteristic thickening in the uterine wall.
Perimenopause
If you’re in your 40s (or sometimes late 30s), perimenopause is a likely explanation. During this transition, estrogen and progesterone rise and fall unpredictably rather than following their usual monthly pattern. You may skip ovulation some months, which throws off the timing and volume of your period. One cycle might be short and light, the next long and heavy. Some months you might skip a period entirely, then have one that lasts ten days.
This phase can last several years before periods stop altogether. The unpredictability is the hallmark. If your formerly reliable cycle has become a guessing game and you’re in the right age range, hormonal shifts from perimenopause are the most common explanation.
Copper IUD and Birth Control Changes
A copper IUD is a well-known cause of longer, heavier periods. Unlike hormonal IUDs, the copper version contains no hormones and works by creating an inflammatory response in the uterus. That inflammation commonly leads to heavier flow, longer bleeding, more cramping, and spotting between periods. These side effects usually ease up after three to six months, but for some people they persist.
Starting or stopping hormonal birth control can also temporarily throw off your cycle. When you first begin a new pill, patch, or ring, your body adjusts to the synthetic hormones over several weeks, and breakthrough bleeding or longer periods are common during that adjustment window. Stopping hormonal contraception after years of use can produce similarly erratic cycles as your body’s natural hormone production resumes.
Bleeding Disorders
This is the cause most people don’t think of. Among women with chronically heavy or prolonged periods, somewhere between 5% and 24% have an underlying bleeding disorder, most commonly von Willebrand disease. This condition affects the blood’s ability to clot properly, and for many women, heavy periods are the first and most obvious symptom. It’s more prevalent among white women (about 16%) than Black women (about 1%) with heavy menstrual bleeding, according to data from the American College of Obstetricians and Gynecologists.
If you’ve had long, heavy periods since your very first cycle, or if you also bruise easily, bleed a lot from cuts, or have had excessive bleeding after dental work or surgery, a bleeding disorder is worth investigating. A simple blood test can check for it.
When Long Periods Cause Anemia
Losing more blood than your body can easily replace puts you at risk for iron deficiency anemia. This is not a rare complication of prolonged periods. It’s common, and many people live with it for months or years without realizing what’s happening. The symptoms creep in gradually: extreme tiredness, weakness, pale skin, feeling dizzy or lightheaded, cold hands and feet, and a fast heartbeat or shortness of breath with normal activity.
Some less obvious signs include brittle nails, a sore tongue, restless legs, and unusual cravings for ice, dirt, or other non-food items. If you’ve been having long periods and any of those symptoms sound familiar, a blood test to check your iron levels can confirm anemia quickly.
How Doctors Figure Out the Cause
The diagnostic process usually starts with a detailed history of your cycles, a pelvic exam, blood work (to check hormone levels, thyroid function, iron levels, and clotting factors), and a transvaginal ultrasound. The ultrasound can reveal fibroids, polyps, adenomyosis, and other structural issues.
If the ultrasound doesn’t give a clear answer, the next step is often a hysteroscopy, where a thin camera is inserted through the cervix to look directly at the inside of the uterus. This can confirm or rule out polyps and other growths that might not show clearly on imaging. In some cases, a small tissue sample is taken during the procedure to check for abnormal cell changes.
Treatment Options
Treatment depends entirely on the cause, but there are effective options across the board. For hormonal imbalances, hormonal birth control (pills, hormonal IUDs, or patches) can regulate the cycle and thin the uterine lining, producing shorter, lighter periods. A hormonal IUD is particularly effective for this because it delivers a small amount of hormone directly to the uterus.
For people who want a non-hormonal option, tranexamic acid is a medication specifically designed to treat heavy menstrual bleeding. It works by preventing blood clots from breaking down too quickly, which reduces bleeding. It’s taken as a tablet only during the days of your period, for a maximum of five days per cycle. One important note: it shouldn’t be combined with combination hormonal contraceptives (the pill, patch, or ring) because the combination increases the risk of blood clots.
Anti-inflammatory pain relievers like ibuprofen can also modestly reduce menstrual flow in addition to helping with cramps. For fibroids or polyps, minor surgical procedures to remove the growths often resolve the problem. Adenomyosis is trickier to treat since the tissue is embedded in the uterine wall, but hormonal therapies can manage symptoms effectively, and for people who are done having children, more definitive surgical options exist.