A normal period lasts about four to five days, and anything beyond seven days is considered prolonged. If your periods regularly stretch past that mark, something is driving it, whether that’s a hormonal imbalance, a structural issue in the uterus, or sometimes an underlying bleeding disorder. The good news is that most causes are identifiable and treatable.
What Counts as a Long Period
The CDC defines heavy menstrual bleeding as periods lasting more than seven days or bleeding heavy enough to soak through a pad or tampon in less than two hours. Most people lose about two to three tablespoons of blood during a normal cycle. Those with prolonged or heavy periods typically lose twice that amount. Passing large clots, especially ones bigger than a quarter, also signals that something beyond normal variation is happening.
This isn’t rare. Estimates of how many people experience heavy or prolonged bleeding range from about 15% to as high as 65%, depending on age group and how the surveys define “heavy.” Women in their 40s and early 50s report it most often, but it can happen at any reproductive age.
Hormonal Imbalances Are the Most Common Cause
Your uterine lining grows and sheds in response to two hormones: estrogen and progesterone. During the first half of your cycle, estrogen thickens the lining to prepare for a potential pregnancy. After ovulation, progesterone rises and stabilizes that lining. If no pregnancy occurs, both hormones drop, and the lining sheds in an orderly way. That’s a normal period.
The trouble starts when ovulation doesn’t happen. Without ovulation, progesterone never kicks in. Estrogen keeps building the lining thicker and thicker with no signal to stop. When that overgrown lining finally breaks down, it sheds unevenly and takes much longer. This is one of the most common explanations for periods that drag on for eight, ten, or even fourteen days. Over time, chronic estrogen exposure without progesterone can lead to a condition called endometrial hyperplasia, where the lining cells crowd together and may become abnormal.
PCOS and Skipped Ovulation
Polycystic ovary syndrome is one of the biggest reasons people skip ovulation regularly. In PCOS, developing follicles in the ovaries stall out before they mature enough to release an egg. This creates a cycle of elevated estrogen and excess androgen production without the balancing effect of progesterone. The result is often irregular cycles: you might go weeks or months without a period, then have one that’s unusually long and heavy when the built-up lining finally sheds.
If your long periods come with irregular cycles, acne, excess hair growth, or difficulty losing weight, PCOS is worth investigating with your doctor.
Perimenopause Changes the Rules
If you’re in your late 30s to early 50s and your periods have recently gotten longer or heavier, perimenopause is a likely explanation. During this transition, estrogen and progesterone fluctuate unpredictably. You may ovulate some months and skip others. When you skip ovulation, the same mechanism applies: the lining keeps growing without progesterone to rein it in, and the resulting period is longer and heavier than usual.
Perimenopause can last several years before periods stop entirely. During that window, it’s normal for your cycle length, flow, and duration to vary dramatically from month to month. Some periods may be short and light, others prolonged and heavy. The unpredictability itself is a hallmark of this phase.
Structural Problems in the Uterus
Sometimes the issue isn’t hormonal at all. Fibroids (noncancerous growths in the uterine wall) and polyps (small growths on the uterine lining) can both increase the surface area that bleeds during a period or interfere with the uterus’s ability to contract and stop bleeding. These are extremely common, particularly in people over 30, and they’re a frequent finding when someone gets evaluated for prolonged periods.
Adenomyosis, a condition where the tissue that normally lines the uterus grows into the muscular wall, can also cause heavy, drawn-out bleeding along with significant cramping. It’s often underdiagnosed because it doesn’t always show up clearly on standard imaging.
Bleeding Disorders Are Underdiagnosed
This is the cause most people don’t consider. In a study of 200 adolescents evaluated for heavy menstrual bleeding, 33% were diagnosed with an underlying bleeding disorder. The most common was low levels of von Willebrand factor, a protein that helps blood clot, found in 16% of the group. Another 11% had von Willebrand disease, and about 5% had platelet dysfunction.
If your periods have been long and heavy since your very first one, or if you bruise easily, bleed a lot from dental work or minor cuts, or have a family history of bleeding problems, a bleeding disorder may be contributing. A simple blood test can check for it, but many people go years without being screened because heavy periods are often dismissed as “just how things are.”
Thyroid Problems and Other Medical Causes
An underactive thyroid can slow down many body processes, including the hormonal signals that regulate your cycle. Hypothyroidism is a well-established cause of prolonged and heavy bleeding. It’s easily detected with a blood test and treatable, making it one of the simplest causes to rule out or address.
Certain medications can also extend your periods. Blood thinners, some anti-inflammatory drugs, and even copper IUDs are known to increase bleeding duration and volume, particularly in the first several months of use.
What Testing Looks Like
If you bring up prolonged periods with your doctor, the workup typically starts with blood tests checking for iron deficiency, thyroid function, and clotting problems. An ultrasound of the uterus and ovaries is standard to look for fibroids, polyps, or ovarian cysts. In some cases, a more detailed procedure called a sonohysterogram is used, where fluid is gently placed inside the uterus to get a clearer ultrasound picture of the lining.
For people over 35 or those with risk factors, an endometrial biopsy may be recommended. This involves taking a small tissue sample from the uterine lining to check for hyperplasia or precancerous changes. A hysteroscopy, where a thin camera is inserted through the cervix, allows direct visualization of the uterine cavity and can identify polyps or fibroids that imaging might miss.
The Iron Connection
One of the most practical consequences of prolonged periods is iron depletion. Every period costs you iron, and when your bleeding lasts longer or is heavier than normal, the loss outpaces what you can replace through diet alone. Over time, your iron stores (measured by a protein called ferritin) drop. Levels below 30 are considered deficient. Eventually, this progresses to full iron-deficiency anemia, where your body can’t produce enough oxygen-carrying capacity in your red blood cells.
Symptoms of low iron overlap with things many people chalk up to being busy or tired: fatigue, brain fog, cold hands and feet, shortness of breath during exercise, and brittle nails. If your periods have been long for a while, checking your ferritin level (not just a basic blood count) is worth doing. Many people with prolonged periods are walking around iron-depleted without realizing it.
How Prolonged Periods Are Managed
Treatment depends entirely on the cause. Hormonal options, including birth control pills, hormonal IUDs, and progesterone-only treatments, work by stabilizing the uterine lining so it doesn’t overgrow. These are the most common first-line approach, especially when the underlying issue is anovulation or hormonal imbalance.
For people who prefer a non-hormonal option, there are medications that work by preventing blood clots from breaking down too quickly, which reduces bleeding. These are taken only during the days of your period, typically for up to five days per cycle. If fibroids or polyps are identified as the cause, removing them often resolves the problem. For adenomyosis or severe cases that don’t respond to other treatments, surgical options ranging from targeted procedures to hysterectomy may be discussed.
The most important step is not assuming prolonged periods are something you just have to live with. A period that consistently exceeds seven days has a reason behind it, and identifying that reason opens the door to targeted treatment that can make a significant difference in daily life and long-term health.