A normal period lasts between three and seven days. Bleeding that continues beyond seven days is considered prolonged by medical standards and falls under the umbrella of heavy menstrual bleeding, or menorrhagia. While some variation from cycle to cycle is completely normal, consistently long periods often point to an underlying cause worth investigating.
What Counts as a Normal Period
Most people bleed for three to seven days each cycle, with the heaviest flow typically occurring in the first two or three days before tapering off. The full menstrual cycle, measured from the first day of one period to the first day of the next, ranges from 21 to 35 days, with 28 days being the average. Both the length of bleeding and the overall cycle length can shift slightly from month to month without signaling a problem.
What matters more than any single period is the pattern over time. If your periods are consistently around the same length and flow, even if they land at the shorter or longer end of that three-to-seven-day window, that’s your normal. It’s when things change noticeably, or when bleeding regularly pushes past seven days, that it’s worth paying attention.
Why Some Periods Last Longer Than Seven Days
Prolonged bleeding has a range of possible causes, from hormonal shifts to structural changes in the uterus. Here are the most common ones.
Hormonal imbalance and missed ovulation. When your body doesn’t ovulate during a cycle, it doesn’t produce progesterone the way it normally would. Without that hormonal signal, the uterine lining keeps building up and eventually sheds irregularly, often resulting in heavier or longer bleeding. This is especially common during puberty, perimenopause, and in people with conditions like PCOS or hypothyroidism.
Uterine fibroids. These noncancerous growths develop in the muscular wall of the uterus, most often during the childbearing years. Fibroids can cause heavier than normal flow and bleeding that drags on well past a week.
Polyps. Small growths on the uterine lining, polyps can trigger prolonged periods, bleeding between periods, and spotting after menopause. Like fibroids, they’re usually benign but can significantly affect how long you bleed.
Adenomyosis. In this condition, the tissue that normally lines the uterus grows into the muscular wall itself. It tends to cause both heavy and prolonged bleeding along with significant cramping.
Bleeding disorders. Conditions like von Willebrand’s disease prevent blood from clotting properly. People with undiagnosed bleeding disorders sometimes don’t realize the connection until they notice their periods are consistently heavier and longer than what others experience.
Medications. Blood thinners, aspirin, and even some hormonal birth control pills can increase menstrual bleeding duration. Hormonal medications that contain estrogen and progestin typically reduce flow but can sometimes cause unexpected or prolonged bleeding instead.
Copper IUD. A copper IUD commonly increases period heaviness and duration, particularly in the first year after insertion. For most people, bleeding patterns settle closer to their pre-IUD normal after that initial adjustment period.
Other causes. Endometriosis, pelvic inflammatory disease, ectopic pregnancy, and miscarriage can all cause prolonged or unusually heavy bleeding. In some cases, no clear cause is identified.
How PCOS Affects Bleeding Duration
PCOS deserves special attention because it changes the nature of bleeding itself. With PCOS, ovulation often doesn’t happen, so the uterine lining keeps thickening over weeks or even months without shedding. Eventually, the body can’t hold onto all that tissue, and it releases unpredictably. The resulting bleeding can last more than 10 days, sometimes stretching to two weeks.
This bleeding isn’t technically a true period, since ovulation never occurred. It’s withdrawal bleeding triggered by the sheer buildup of tissue. Because so much lining has accumulated, the flow tends to be both heavy and prolonged. Many people with PCOS assume this is just how their period works, but it’s a sign that hormonal management could help.
How Periods Change During Perimenopause
As you approach menopause, typically in your 40s, fluctuating hormone levels make periods less predictable. They may get longer, shorter, heavier, lighter, or skip entirely. In early perimenopause, the length of your cycle starts shifting by seven days or more compared to what you’re used to. In late perimenopause, gaps of 60 days or more between periods are common.
Some perimenopausal periods can feel dramatically different from what you’ve experienced for decades, and that’s often within the range of expected changes. That said, bleeding that lasts longer than seven days during perimenopause still warrants evaluation, as does any cycle that consistently comes fewer than 21 days apart. These patterns can overlap with conditions like polyps or thickened uterine lining that become more relevant with age.
Signs Your Period Is Too Heavy
Duration is only part of the picture. A period that lasts the full seven days but involves light flow is very different from one that has you soaking through a pad or tampon nearly every hour. The CDC defines heavy menstrual bleeding as periods lasting more than seven days or involving roughly twice the typical blood loss.
A practical way to gauge this: if you’re changing your pad or tampon every hour for several consecutive hours, or passing blood clots larger than a quarter, your bleeding is heavier than normal.
Over time, prolonged or heavy periods can drain your iron stores. Iron deficiency anemia develops gradually and can cause extreme tiredness, weakness, pale skin, dizziness, shortness of breath, cold hands and feet, and brittle nails. Some people develop unusual cravings for ice, dirt, or other non-food items. If you regularly have long or heavy periods and recognize these symptoms, low iron is a likely contributor.
How Prolonged Bleeding Is Evaluated
When bleeding consistently lasts more than seven days or is unusually heavy, evaluation typically starts with blood work to check hormone levels, thyroid function, and iron status, along with a pelvic ultrasound to look for structural issues like fibroids or polyps. A specialized ultrasound using saline to expand the uterine cavity can give a clearer view of the lining.
For people over 35 with prolonged bleeding, or younger people with risk factors like obesity, chronic irregular cycles, or diabetes, an endometrial biopsy may be recommended. This involves taking a small tissue sample from the uterine lining to rule out abnormal cell growth. If imaging and initial treatments don’t resolve the problem, direct visualization of the uterine interior through hysteroscopy is the next step.
The diagnostic path depends heavily on your age, risk factors, and whether initial treatments help. Many causes of prolonged bleeding are highly treatable once identified, ranging from hormonal management for ovulation issues to minimally invasive procedures for fibroids or polyps.