A normal period lasts between 2 and 7 days. Bleeding that continues beyond 7 days is considered prolonged, and it warrants a closer look at what’s going on. While a single longer-than-usual period isn’t always a sign of something serious, regularly bleeding for more than a week points to an underlying cause that can and should be identified.
What Counts as a Normal Period
Most periods fall in a range of 2 to 7 days, with cycles repeating every 21 to 35 days. Within that window, there’s a lot of variation from person to person, and even from month to month. A period that runs 6 or 7 days is still within the normal range, even if it feels long compared to a friend who wraps up in 3 days.
The clinical threshold is 7 days. Once bleeding regularly extends past that, it falls under what doctors call prolonged menstrual bleeding. The volume matters too. Losing more than about 80 milliliters of blood per period (roughly 2.7 ounces, or about a third of a cup) is classified as heavy menstrual bleeding, and prolonged periods and heavy flow often go hand in hand.
Signs Your Bleeding Is Too Heavy
Tracking days on a calendar is one thing, but the practical signs of a problem are often easier to notice in daily life. According to the CDC, you may have abnormally heavy bleeding if you:
- Soak through a pad or tampon every hour for several hours in a row
- Need to change pads or tampons during the night
- Have to double up on pads to stay protected
- Pass blood clots the size of a quarter or larger
- Feel too limited by your period to go about your normal routine
Over time, heavy or prolonged bleeding can lead to iron-deficiency anemia. If you’re feeling unusually tired, weak, or short of breath alongside long periods, that fatigue may not just be from the inconvenience of bleeding. Your body could be running low on the red blood cells it needs to carry oxygen efficiently.
Why Periods Last Longer Than They Should
Several different problems can extend bleeding beyond the 7-day mark. They generally fall into a few categories: structural issues in the uterus, hormonal imbalances, bleeding disorders, and outside factors like certain contraceptives.
Fibroids and Polyps
Uterine fibroids are noncancerous growths in the muscular wall of the uterus, and they’re one of the most common causes of prolonged, heavy periods. They cause extra bleeding through several mechanisms. A fibroid can increase the total surface area of the uterine lining, meaning there’s simply more tissue to shed. Fibroids also compress surrounding blood vessels, creating enlarged pools of blood within the uterine wall that are prone to leaking. The blood vessels that form around fibroids tend to be structurally fragile, lacking the reinforcement that normal blood vessels have, which makes them more likely to break open during a period.
Fibroids can also interfere with the uterus’s ability to contract properly. Those contractions are what helps stop bleeding after the lining sheds, so when they’re disrupted, bleeding drags on. On top of that, fibroids release chemical signals that reduce the activity of clotting factors in the surrounding tissue, making it harder for the body to seal off bleeding on its own.
Polyps, which are smaller growths on the uterine lining itself, cause similar problems on a smaller scale. They create extra vascular tissue that bleeds easily and can extend the number of days you bleed each cycle.
Hormonal Imbalances
Your period depends on a carefully timed sequence of hormonal signals. When that sequence is disrupted, the uterine lining can build up unevenly and shed irregularly, leading to prolonged or unpredictable bleeding.
Polycystic ovary syndrome (PCOS) is a common culprit. In PCOS, ovulation doesn’t happen regularly, which means the hormone that normally triggers a clean, complete shedding of the lining never arrives on schedule. The lining keeps thickening until it eventually breaks down on its own, often resulting in longer, heavier, and less predictable bleeding.
Thyroid problems can trigger the same pattern. An underactive thyroid disrupts the hormonal chain reaction that controls ovulation, leading to irregular cycles, breakthrough bleeding, and periods that go on longer than they should. It can also cause the uterine lining to thin in some cases while paradoxically causing heavier, more prolonged shedding when it does occur.
Bleeding Disorders
Sometimes the issue isn’t with the uterus at all but with the blood’s ability to clot. Von Willebrand disease, the most common inherited bleeding disorder, is found in an estimated 5% to 20% of women who experience chronic heavy periods. Many of these women go years without a diagnosis because heavy periods are often dismissed as “just how it is.” If your periods have been unusually long and heavy since your very first cycle, or if you also bruise easily or bleed a lot from minor cuts, a bleeding disorder is worth investigating.
Copper IUDs
If your periods got noticeably longer after getting an IUD, the type matters. Copper IUDs can increase both the heaviness and the duration of menstrual bleeding, especially in the first few months after insertion. Hormonal IUDs tend to have the opposite effect, often making periods lighter or stopping them entirely over time. If you have a copper IUD and your periods are consistently running past 7 days, that could be the explanation, though it’s still worth confirming with your provider.
Perimenopause Changes the Rules
If you’re in your 40s and your periods are becoming longer or more erratic, perimenopause is a likely factor. During the transition to menopause, ovulation becomes less reliable, and cycle length starts to shift. Research tracking women through this transition found that cycle length begins increasing as early as 7.5 years before the final menstrual period, with the steepest changes occurring in the last 4 years. About 38% of women experience a noticeable increase in cycle length during this window.
These changes happen because the ovaries are producing fewer consistent hormonal signals. Cycles without ovulation become more common, which can lead to the same kind of uneven lining buildup and irregular shedding seen in PCOS. Some months you might barely bleed, and other months the bleeding seems to go on forever. This variability is a hallmark of perimenopause, but prolonged bleeding during this stage still deserves evaluation, particularly because the risk of uterine lining abnormalities increases with age.
How Prolonged Bleeding Is Evaluated
When you report periods lasting longer than 7 days, the first step is typically a transvaginal ultrasound. This is the standard initial test for spotting structural problems like fibroids or polyps. It’s noninvasive and gives a clear picture of the uterine wall and lining.
If the ultrasound is inconclusive or suggests something inside the uterine cavity, the next step may be a saline infusion sonography, where a small amount of fluid is used to expand the uterus for a better view. Hysteroscopy, which involves a tiny camera passed through the cervix, provides direct visualization and allows for biopsies or removal of polyps during the same procedure. It’s typically reserved for cases where earlier imaging raises concerns.
For women 45 and older, or when initial treatments aren’t working, an endometrial biopsy is often recommended to check the uterine lining for abnormal cell growth. Blood work to check thyroid function, hormone levels, and clotting factors rounds out the picture when hormonal or systemic causes are suspected.
What You Can Track Before Your Appointment
If you’re noticing your periods stretching past a week, keeping a simple log before your appointment makes the conversation much more productive. Note the number of days you bleed, how often you change your pad or tampon (and how saturated it is), whether you pass clots, and any symptoms like fatigue or dizziness. Even two or three cycles of data gives your provider a much clearer starting point than trying to recall patterns from memory.