A period that drags on past its usual length is almost always a sign that your uterine lining isn’t shedding efficiently, and hormonal shifts are the most common reason why. Normal periods last between two and seven days. If yours regularly stretches beyond seven days, or if a period that used to wrap up in four or five days is now hanging around for a week or more, something has changed in the signals your body uses to build up and shed that lining each month.
The causes range from simple and temporary (stress, a new contraceptive) to conditions worth investigating with a doctor. Here’s what could be behind it.
How Hormones Control When Bleeding Stops
Your period isn’t just blood flowing freely. It’s a tightly choreographed process. In the first half of your cycle, estrogen thickens the uterine lining to prepare for a possible pregnancy. After ovulation, progesterone rises and stabilizes that lining. If no pregnancy occurs, both hormones drop, and the lining sheds in an organized way. That’s your period.
When progesterone is too low relative to estrogen, the lining grows thicker than it should but doesn’t get the clear hormonal signal to shed all at once. Instead, it breaks down unevenly and slowly, producing the kind of bleeding that starts, seems to taper off, then keeps spotting for days. This estrogen-progesterone imbalance is the single most common driver of a lingering period, and it sits behind many of the specific conditions below.
Cycles Without Ovulation
If you don’t ovulate in a given month, your body never produces the progesterone surge that normally follows. Without progesterone, the uterine lining keeps growing under the influence of estrogen but has no mechanism to shed cleanly. Eventually it breaks down on its own in irregular patches, causing prolonged, unpredictable bleeding that can feel like a period that simply won’t end.
Polycystic ovary syndrome (PCOS) is responsible for roughly 70% of anovulatory cycles. PCOS causes elevated androgens that prevent follicles in the ovaries from maturing enough to release an egg. But you don’t need PCOS to skip ovulation. High stress, significant weight changes, over-exercising, and even illness can suppress ovulation for a cycle or two, leading to that same drawn-out bleed.
Perimenopause
If you’re in your late 30s or 40s, perimenopause is one of the likeliest explanations. As your ovaries begin winding down, estrogen and progesterone levels fluctuate unpredictably. Ovulation becomes inconsistent. Some months you may ovulate normally and have a textbook period; other months you won’t ovulate at all, and bleeding drags on or arrives at odd intervals.
An early sign of perimenopause is a cycle length that shifts by seven or more days compared to what’s been normal for you. Flow can swing from light to very heavy, and periods may linger longer than they used to. Some women notice these changes as early as their mid-30s, though the 40s are more typical. Once you’re going 60 or more days between periods, you’ve likely moved into late perimenopause.
Fibroids and Polyps
Structural growths inside the uterus can physically interfere with the lining’s ability to shed and the uterus’s ability to contract and close off blood vessels afterward. Uterine polyps are soft growths attached to the inner wall that are estrogen-sensitive, meaning they grow in response to estrogen circulating in your body. They cause irregular bleeding, very heavy flow, and spotting between periods.
Fibroids, which are noncancerous muscle growths in the uterine wall, work similarly. Depending on their size and location, they can distort the uterine cavity, increase the surface area of the lining, and prevent the uterus from clamping down effectively to stop bleeding. Both fibroids and polyps are extremely common, and many people don’t know they have them until prolonged or heavy bleeding prompts an ultrasound.
Thyroid Problems
Your thyroid acts as a master regulator for metabolism, and when it’s underactive (hypothyroidism), processes throughout your body slow down. That includes the hormonal signaling that governs your cycle. Low thyroid hormone can alter how your blood clots, potentially leading to heavier, longer-lasting periods. Some people with hypothyroidism notice periods becoming irregular, heavier, or more frequent, sometimes arriving more than once a month.
Thyroid disorders are straightforward to test for with a simple blood draw, which is why they’re often one of the first things a provider checks when someone reports a change in menstrual patterns.
Your IUD or Contraceptive Method
A copper IUD is well known for making periods heavier and longer, especially in the first year after insertion. It takes three to six months for your body to adjust to any IUD, and some people experience noticeably heavier flow during that entire first year. After that, periods typically settle back closer to your baseline.
Starting, stopping, or switching hormonal contraceptives (the pill, patch, ring, or hormonal IUD) can also cause breakthrough bleeding or prolonged spotting while your body adjusts to the new hormone levels. This usually resolves within two to three months, but if it doesn’t, it’s worth a conversation with your provider about switching methods.
Bleeding Disorders
A less obvious but underdiagnosed cause is a blood clotting disorder. Von Willebrand disease, the most common inherited bleeding disorder, affects how well your blood forms clots. Among women with chronic heavy menstrual bleeding, between 5% and 24% turn out to have von Willebrand disease. Many aren’t diagnosed until adulthood because heavy periods were dismissed as normal for them. If you’ve always had periods that seem heavier or longer than everyone else’s, and you also bruise easily or bleed a long time from minor cuts, a clotting disorder is worth ruling out.
Why Prolonged Bleeding Matters
Beyond the inconvenience, a period that lingers carries real health consequences. The most immediate risk is iron deficiency anemia. Heavy menstrual bleeding is clinically defined as losing more than 80 milliliters of blood per cycle, roughly equivalent to soaking through a pad or tampon every hour for several consecutive hours. Over months, this steady blood loss depletes your iron stores.
Anemia from period-related blood loss shows up as fatigue that doesn’t improve with sleep, shortness of breath during normal activities, dizziness, pale skin, and feeling cold when others are comfortable. Many people attribute these symptoms to being busy or stressed and don’t connect them to their periods. If your period has been running long and you’re experiencing any of these, ask for a ferritin level check (a blood test that measures stored iron) in addition to a standard blood count.
What Gets Checked
When you bring up prolonged bleeding, a provider will typically start with blood work to check your thyroid, hormone levels, and blood count. For women over 45, or younger women with risk factors like obesity or PCOS, an endometrial tissue sample may be recommended to rule out abnormal thickening of the lining. A pelvic ultrasound can identify fibroids, polyps, or other structural issues that might be contributing.
The specific workup depends on your age, symptoms, and history. If you’ve had prolonged bleeding that hasn’t responded to initial treatment, or if the pattern keeps recurring, further evaluation is standard. Keeping a record of how many days you bleed, how heavy the flow is, and how many pads or tampons you go through gives your provider concrete information to work with, since “heavy” and “long” mean different things to different people.