A period lasting longer than seven days is considered prolonged and has a medical name: menorrhagia. While an occasional long cycle can be harmless, consistently bleeding beyond a week usually points to something specific, whether that’s a hormonal shift, a structural change in the uterus, or sometimes a bleeding disorder. Understanding the most likely causes can help you figure out what’s going on and what to do about it.
What Counts as a Normal Period
A typical period lasts between three and seven days. The total blood loss during a normal cycle is under 80 milliliters, roughly five to six tablespoons. Once bleeding regularly exceeds seven days or becomes heavy enough that you’re soaking through a pad or tampon every hour for several hours, it crosses into abnormal territory. That doesn’t automatically mean something dangerous is happening, but it does mean there’s a reason worth identifying.
Hormonal Imbalances
The most common explanation for prolonged periods is a hormonal imbalance, specifically one that disrupts ovulation. In a normal cycle, your ovaries release an egg, and the hormone progesterone rises to stabilize the uterine lining. When ovulation doesn’t happen (called an anovulatory cycle), progesterone stays low. Without that counterbalance, estrogen continues building up the lining of the uterus unchecked. When the lining finally sheds, the bleeding is heavier and takes longer.
Two conditions frequently cause this pattern:
- Polycystic ovary syndrome (PCOS) interferes with regular ovulation. Cycles may be irregular, skipped entirely, or followed by prolonged heavy bleeding when the thickened lining finally sheds.
- Thyroid problems, especially an underactive thyroid, can lead to irregular and heavy menstrual bleeding, spotting between periods, and ovulation disorders. Hypothyroidism disrupts the hormonal signals that regulate your cycle, including raising levels of a hormone called prolactin that can interfere with normal ovulation.
Both conditions are treatable, and managing them typically brings periods back to a more predictable length.
Fibroids and Polyps
Growths inside or on the uterus are another frequent cause. Uterine fibroids are noncancerous muscle tumors 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. Polyps are smaller tissue growths on the inner lining that cause prolonged bleeding through a different mechanism.
Endometrial polyps are made of tissue that doesn’t respond normally to your monthly hormonal signals. Unlike the rest of the uterine lining, polyps resist the natural process of shedding during menstruation. They also have altered hormone receptors in their tissue, which prevents them from going through the normal breakdown cycle. The result is persistent or irregular bleeding that can extend your period well past seven days. The bleeding from polyps is often caused by congestion within the polyp’s blood vessels, leading to tissue breakdown at the surface.
Both fibroids and polyps are common, especially in women over 30, and can be identified through ultrasound.
Perimenopause
If you’re in your late 30s or 40s and your periods have become unpredictable, perimenopause is a likely factor. During this transition, the ovaries gradually produce less estrogen, but the decline isn’t smooth. You may have cycles where estrogen runs higher than normal without enough progesterone to balance it, causing the uterine lining to build up excessively.
The pattern varies widely. Some months your period might be shorter and lighter. Other months it could last 10 days and be significantly heavier. You might skip periods entirely, then have a prolonged one. This phase can last several years before menopause, and the irregular bleeding is one of the most common symptoms women experience during it.
One concern during perimenopause is endometrial hyperplasia, a condition where the uterine lining becomes abnormally thick due to estrogen dominance. This matters because atypical forms of endometrial hyperplasia carry a meaningful risk of progressing to uterine cancer if left untreated, roughly 8% per year. Prolonged or recurrent bleeding during perimenopause is worth investigating for this reason alone.
Your IUD Could Be the Cause
If you recently had an IUD placed, it could be extending your period. Copper IUDs are well known for increasing menstrual bleeding, and heavier, longer periods are the most common reason women have them removed within the first six months. The copper creates a mild inflammatory response in the uterus that leads to more bleeding.
Hormonal IUDs that release progestin tend to have the opposite long-term effect, eventually making periods lighter or stopping them altogether. But in the first few months after insertion, they can cause irregular bleeding and spotting that may feel like an extended period. This usually improves within three to six months as your body adjusts.
Bleeding Disorders
A cause that often goes undiagnosed for years is an underlying bleeding disorder. Von Willebrand disease, the most common inherited bleeding condition, affects how well your blood clots. Among women with chronic heavy or prolonged menstrual bleeding, somewhere between 5% and 24% are eventually found to have this condition. The prevalence appears to vary by ethnicity, with studies showing higher rates among white women (around 16%) compared to Black women (about 1%).
Signs that a bleeding disorder might be behind your long periods include a history of easy bruising, prolonged bleeding after dental work or surgery, frequent nosebleeds, or a family history of bleeding problems. If you’ve had heavy periods since your very first cycle as a teenager, that’s another clue worth mentioning to your doctor.
When Prolonged Bleeding Becomes Dangerous
The most immediate risk of consistently long or heavy periods is iron deficiency anemia. Your body loses iron with every milliliter of blood, and when periods regularly exceed normal volume, your iron stores can drop below what your body needs to function. Symptoms include fatigue that doesn’t improve with rest, shortness of breath during mild activity, dizziness, pale skin, cold hands and feet, and difficulty concentrating. Many women with prolonged periods assume their tiredness is just stress or poor sleep when it’s actually low iron.
Certain signs during a prolonged period warrant prompt attention: soaking through a pad or tampon every hour for more than two consecutive hours, passing blood clots larger than a quarter, feeling lightheaded or faint, or having a resting heart rate that feels unusually fast. These can indicate significant blood loss that may need intervention to prevent further decline.
How Prolonged Periods Are Treated
Treatment depends entirely on what’s causing the extended bleeding, which is why getting the right diagnosis matters more than trying to manage the symptom on your own.
For hormonal imbalances, hormonal birth control (pills, patches, or a hormonal IUD) is often the first approach. These methods regulate the cycle by providing steady hormone levels and keeping the uterine lining thin. For PCOS or thyroid disorders, treating the underlying condition usually resolves the prolonged bleeding as a secondary benefit.
For heavy bleeding itself, a medication that helps blood clot more effectively can reduce menstrual blood loss by 26% to 60%, making it one of the most effective options for managing volume. Anti-inflammatory pain relievers can also modestly reduce bleeding, though they tend to be less effective on their own.
Fibroids and polyps can often be removed through minimally invasive procedures, sometimes done in an office setting. For endometrial hyperplasia, treatment ranges from progesterone therapy to monitor and reverse the thickening, to more involved procedures if atypical cells are found.
If your period has been lasting longer than seven days for more than two or three cycles, tracking the pattern (how many days, how heavy, any clots, any symptoms between periods) gives your doctor practical information to work with. A combination of blood work, ultrasound, and sometimes a biopsy of the uterine lining can usually pinpoint the cause.