A period that lasts longer than 7 days crosses the clinical threshold for what’s considered prolonged menstrual bleeding. While an occasional longer cycle isn’t always a sign of something serious, bleeding that consistently extends past a week, or that suddenly does so when it never has before, points to an underlying cause worth investigating. The most common reasons range from hormonal imbalances to structural changes in the uterus, and some are easier to address than you might expect.
What Counts as Too Long
A typical period lasts between 3 and 7 days. Once bleeding extends beyond that 7-day mark, it meets the criteria for menorrhagia, a term for heavy or prolonged menstrual bleeding. The other defining feature is total blood loss exceeding about 80 mL per cycle, roughly the equivalent of soaking through a pad or tampon every hour for several consecutive hours. But even if the flow isn’t unusually heavy, duration alone is enough to qualify.
Some practical signs that your bleeding has crossed into concerning territory: soaking through one or more pads or tampons every hour for several hours straight, needing to double up on pads, waking at night to change protection, or passing blood clots the size of a quarter or larger. Any of these patterns alongside bleeding past day 7 warrants a closer look.
Hormonal Imbalance Is the Most Common Cause
Your menstrual cycle depends on a balance between estrogen and progesterone. Estrogen builds up the uterine lining each month, and progesterone stabilizes it and triggers an orderly shed when levels drop. When that balance tips, the lining can grow thicker than normal and shed unevenly, leading to bleeding that drags on longer than it should.
The most frequent disruption is a cycle where you don’t ovulate. Ovulation is the trigger for your body to produce progesterone. Without it, estrogen continues building the lining unopposed, and when bleeding finally starts, there’s simply more tissue to shed. This can happen during times of stress, significant weight changes, intense exercise, or conditions like polycystic ovary syndrome. The result is often a period that’s both heavier and longer than usual, sometimes with unpredictable spotting between cycles as well.
Perimenopause Changes the Rules
If you’re in your 40s (or sometimes late 30s), hormonal shifts related to perimenopause are a leading explanation. As ovulation becomes less reliable, progesterone production drops while estrogen can remain high or fluctuate wildly. This creates the same “unopposed estrogen” pattern: the uterine lining thickens excessively, and periods become heavier, longer, or irregular.
A condition called endometrial hyperplasia, where the uterine lining becomes abnormally thick, is most common during this transition for exactly this reason. Bleeding that’s heavier than your normal pattern or that lasts more days than usual during perimenopause is not something to dismiss as “just part of the change.” It can usually be managed, but it needs evaluation because in a small percentage of cases, hyperplasia can progress to precancerous changes.
Structural Problems in the Uterus
Sometimes the issue isn’t hormonal but physical. Two conditions in particular are known for extending bleeding well past a week.
Fibroids are noncancerous growths in the uterine wall. They’re extremely common, especially in women over 30, and depending on their size and location, they can distort the uterine lining and cause prolonged, heavy periods. Submucosal fibroids, the type that grows into the uterine cavity, are the most likely to affect bleeding.
Adenomyosis occurs when tissue that normally lines the uterus starts growing into the muscular wall. This thickens the wall and often enlarges the entire uterus, leading to heavy menstrual bleeding, periods that last longer than usual, and painful cramping both during your period and sometimes throughout the cycle. It’s frequently diagnosed in women in their 30s and 40s, and it’s often mistaken for fibroids because the symptoms overlap. The distinguishing feature is that the pain tends to be more constant and the uterus feels uniformly enlarged and tender, rather than having distinct lumps.
Birth Control Can Be the Culprit
If you recently started or changed a contraceptive method, that’s a likely explanation. The copper IUD is particularly notorious for causing heavier, longer, and more painful periods, especially in the first several months after insertion. These side effects typically ease up after three to six months as your body adjusts, but some women find the change in bleeding persists longer.
Hormonal birth control methods, including the pill, hormonal IUDs, implants, and injections, can also cause irregular or prolonged bleeding during the adjustment period. Breakthrough bleeding or extended spotting is common in the first three months of any new hormonal method. If bleeding beyond 7 days started around the time you began a new contraceptive, give it a few cycles before worrying, but mention it to your provider if it continues past that window.
Bleeding Disorders and Thyroid Problems
Some women bleed longer because their blood doesn’t clot efficiently. Von Willebrand disease is the most common inherited bleeding disorder in women, and heavy menstrual bleeding is its hallmark symptom. Between 74% and 92% of women diagnosed with this condition report abnormally heavy periods. It’s caused by a deficiency in a protein needed for platelets to stick together properly, and it often goes undiagnosed for years because heavy periods get normalized or attributed to other causes. If you’ve always had prolonged or heavy periods, bruise easily, or bleed excessively after dental work or minor injuries, a bleeding disorder is worth screening for.
Thyroid dysfunction is another systemic cause. Both an underactive and overactive thyroid can disrupt menstrual patterns. Hypothyroidism in particular slows the body’s metabolic processes in ways that interfere with the hormonal signaling that controls your cycle, often resulting in heavier, longer periods.
When Prolonged Bleeding Isn’t a Period
Not all vaginal bleeding is menstrual. If there’s any chance you could be pregnant, bleeding that you assume is a long period could actually signal a complication. Early miscarriage often presents as heavier-than-normal bleeding with cramping, and it’s easy to mistake for a late, heavy period, especially if you didn’t know you were pregnant.
Ectopic pregnancy, where a fertilized egg implants outside the uterus (usually in a fallopian tube), often begins with light vaginal bleeding and pelvic pain. If the ectopic pregnancy progresses, it can cause a rupture with severe internal bleeding. Severe abdominal or pelvic pain accompanied by vaginal bleeding is an emergency and requires immediate medical attention.
How Prolonged Bleeding Gets Diagnosed
If you see a provider about bleeding past 7 days, expect a workup that starts simple and gets more targeted based on what turns up. Blood tests come first, checking for iron deficiency anemia (a common consequence of prolonged bleeding), thyroid disorders, and clotting problems. A Pap smear may be done to check for cervical changes.
Ultrasound is the standard imaging tool, giving a clear picture of your uterus and ovaries to check for fibroids, adenomyosis, or other structural issues. If the ultrasound raises questions about the uterine lining, you may be offered a sonohysterography, where fluid is injected into the uterus to get a clearer view of the lining, or a hysteroscopy, where a thin camera is inserted through the cervix to look directly inside. An endometrial biopsy, a small tissue sample from the uterine lining, checks for precancerous changes or other abnormalities and is especially important for women over 35 or those with risk factors for endometrial hyperplasia.
The cause shapes the treatment. Hormonal imbalances are often managed with hormonal therapies that regulate the cycle. Fibroids and adenomyosis have a range of options from medication to procedures. Bleeding disorders are managed with targeted therapies that improve clotting. The first step is always figuring out which category you fall into, and that starts with a conversation and basic testing.