A period that lasts longer than 7 days is considered prolonged by medical standards, and anything beyond that timeframe has a cause worth identifying. Normal menstrual bleeding runs 4 to 7 days and produces less than 80 mL of blood loss per cycle (roughly 16 soaked regular tampons or pads across the whole period). If yours has stretched well past a week, or you’re soaking through a pad or tampon every hour or two, something is disrupting your body’s normal process of building and shedding the uterine lining.
The causes range from hormonal imbalances that are simple to correct to structural changes in the uterus that may need closer evaluation. Here’s what could be behind it.
Hormonal Imbalances Are the Most Common Cause
Your period depends on a precise back-and-forth between estrogen and progesterone. Estrogen thickens the uterine lining in the first half of your cycle, and progesterone stabilizes it in the second half. When you don’t ovulate, which can happen for many reasons, your body keeps producing estrogen without enough progesterone to balance it out. The lining grows thicker than usual and eventually sheds unevenly, leading to prolonged or unpredictable bleeding.
Polycystic ovary syndrome (PCOS) is one of the most frequent culprits. With PCOS, ovulation doesn’t happen regularly, so progesterone stays low while estrogen continues building up the lining cycle after cycle. When bleeding finally starts, it can be heavy and drag on for weeks. Obesity compounds this effect because fat tissue produces its own estrogen, tipping the balance further.
Thyroid problems work through a different pathway but produce the same result. Your thyroid gland directly affects your ovaries and also controls a protein called SHBG that carries reproductive hormones through the bloodstream. When thyroid function is too low (hypothyroidism), the brain releases higher levels of a hormone called prolactin, which interferes with your ovaries’ ability to produce estrogen in the right amounts and at the right times. This can cause periods that are heavier, longer, or more erratic than normal. Both an underactive and overactive thyroid can disrupt cycle length.
Growths Inside the Uterus
Uterine polyps and fibroids are physical growths that change how the uterine lining behaves. Polyps are soft tissue growths attached to the inner wall of the uterus, sometimes by a thin stalk, ranging from the size of a sesame seed to as large as a golf ball. They increase the surface area of the lining and can cause heavy, prolonged, or unpredictable bleeding. Fibroids are muscular growths in the uterine wall that can press on the lining, distort the uterine cavity, and prevent the uterus from contracting efficiently to stop bleeding.
Both are common and usually not cancerous, but they don’t tend to resolve on their own. If a polyp or fibroid is the reason your period won’t stop, you’ll typically notice that the problem persists or worsens over several cycles rather than being a one-time event.
Birth Control Can Cause Prolonged Bleeding
If you recently started or changed a hormonal contraceptive, that’s a likely explanation. Breakthrough bleeding is extremely common with IUDs, implants, and hormonal pills, especially in the first few months.
With hormonal IUDs, spotting and irregular bleeding in the first months after placement is normal and usually improves within 2 to 6 months. The implant works differently: the bleeding pattern you experience in the first 3 months tends to be the pattern you’ll have going forward, so if prolonged spotting hasn’t improved after that window, it may not on its own. Missing pills, taking them at inconsistent times, or switching formulations can also trigger extended bleeding episodes.
Bleeding Disorders You May Not Know About
Some people bleed longer simply because their blood doesn’t clot as efficiently. Von Willebrand disease (VWD) is the most common inherited bleeding disorder, affecting up to 1 in 100 people in the United States. Many women don’t get diagnosed until they realize their periods are unusually heavy.
Signs that a bleeding disorder might be involved include soaking through a pad or tampon every 1 to 2 hours on your heaviest days, passing blood clots larger than a grape or strawberry, menstrual bleeding that consistently lasts longer than 7 days, and being told you’re anemic from blood loss. If heavy, prolonged periods run in your family, or if you’ve also noticed that you bruise easily or bleed a long time from cuts, a bleeding disorder is worth investigating.
Endometrial Hyperplasia
When the uterine lining thickens beyond what’s normal and doesn’t shed properly, the condition is called endometrial hyperplasia. This happens when estrogen exposure is high without enough progesterone to keep the lining in check. It’s most common during perimenopause and after menopause, but it also occurs in younger women with PCOS, obesity, irregular cycles, or diabetes. Risk factors include being over 35, never having been pregnant, starting periods at an early age, and having a family history of ovarian, colon, or uterine cancer.
The main symptom is abnormal uterine bleeding, which can mean periods that last far too long, bleeding between periods, or unusually heavy flow. Hyperplasia matters because some forms can progress to uterine cancer if left untreated. That’s why persistent abnormal bleeding, particularly in women 35 and older, typically prompts a tissue sample to rule out precancerous changes.
What Happens When You Get Evaluated
If your period has been going on for more than 7 days, or this has become a recurring pattern, a doctor will typically start with blood work to check your hormone levels, thyroid function, and blood counts (to see if the bleeding has made you anemic). From there, the next step is usually a transvaginal ultrasound, which measures the thickness of your uterine lining and can reveal polyps, fibroids, or other structural issues.
If the ultrasound shows a thickened lining or anything abnormal, or if you’re 35 or older with unexplained bleeding, you may need an endometrial biopsy. This involves taking a small tissue sample from the lining to check for hyperplasia or cancer. In some cases, a procedure called a hysteroscopy (a thin camera inserted through the cervix) gives a direct view of the uterine cavity and can identify growths that ultrasound might miss.
How Prolonged Bleeding Is Treated
Treatment depends entirely on the cause. Hormonal imbalances from PCOS or thyroid disorders are often managed with hormonal contraceptives or progesterone therapy to regulate the cycle and thin the lining. Thyroid medication can restore normal periods when thyroid dysfunction is the root issue.
For active heavy bleeding, a medication that helps blood clot more effectively can reduce menstrual blood loss by about 40% compared to no treatment, based on a large randomized trial. It’s taken as a pill for up to 5 days during the heaviest part of your period.
Polyps and small fibroids can often be removed in a minor procedure through the cervix, with no incision needed. For more severe cases where medication hasn’t worked, endometrial ablation destroys the uterine lining to permanently reduce or stop bleeding. It’s an outpatient procedure with a few days of cramping and discharge, and no hospital stay. A hysterectomy (removing the uterus) is a more definitive option but involves a longer recovery: 3 to 4 weeks for less invasive approaches and 4 to 6 weeks for abdominal surgery.
Signs Your Bleeding Needs Urgent Attention
Prolonged bleeding that goes unchecked can quietly drain your iron stores. If you’re feeling unusually exhausted, lightheaded, short of breath climbing stairs, or notice that your skin looks pale, these are signs of iron deficiency anemia from blood loss. Dizziness or a racing heartbeat at rest suggests more significant blood loss. Soaking through a pad or tampon every hour for several consecutive hours, or passing large clots, warrants same-day medical contact rather than waiting for a scheduled appointment.