A period lasting longer than seven days is considered abnormal uterine bleeding by the American College of Obstetricians and Gynecologists. It’s common enough that it has a clinical name (menorrhagia), and while it’s not always a sign of something serious, it does have identifiable causes that are worth investigating. Most of them are treatable once you know what’s going on.
What Counts as a Long Period
Normal periods last between three and seven days. Once bleeding extends past that seven-day mark, or you’re losing more than about 80 milliliters of blood per cycle (roughly five to six tablespoons), it crosses the threshold into heavy menstrual bleeding. That might sound like a hard number to measure, but there are practical signs: soaking through a pad or tampon every hour for two or more hours in a row, passing blood clots larger than a quarter, or needing to wake up at night to change protection.
A single long period can be a fluke caused by stress, a late ovulation, or a one-off hormonal shift. But if your periods regularly stretch beyond a week, or the pattern has changed noticeably over the past six months, that’s considered chronic abnormal bleeding and points toward an underlying cause.
Hormonal Imbalances
Your menstrual cycle depends on a precise back-and-forth between estrogen and progesterone. Estrogen builds up the uterine lining in the first half of the cycle, and progesterone stabilizes it in the second half, then drops to trigger your period. When that balance is off, the lining can grow thicker than normal or shed unevenly, leading to prolonged or unpredictable bleeding.
This is especially common during two life stages: the first few years of menstruation and the years leading up to menopause (perimenopause). In both cases, ovulation becomes irregular, which means progesterone levels stay low. Without enough progesterone to keep the lining organized, bleeding can drag on. Thyroid disorders and polycystic ovary syndrome (PCOS) also disrupt these hormones and frequently show up as long or heavy periods.
Fibroids and Polyps
Structural growths inside the uterus are one of the most common physical causes of prolonged bleeding. Uterine polyps are overgrowths of the uterine lining that attach to the uterine wall by a base or a thin stalk. They’re estrogen-sensitive, meaning they grow in response to estrogen, and they can cause heavy flow, bleeding between periods, and periods that last longer than usual.
Fibroids are noncancerous muscular growths in or on the uterine wall. They increase the surface area of the lining and can interfere with the uterus’s ability to contract and stop bleeding after a period starts. Both polyps and fibroids are extremely common, particularly in your 30s and 40s, and many people have them without knowing until heavy or prolonged bleeding prompts an evaluation.
Your IUD or Other Medications
The copper IUD is a well-known cause of heavier, longer periods. Because it works without hormones, it creates a low-grade inflammatory response in the uterus that can lead to serious menstrual pain and heavy bleeding, especially during the first few months after insertion. For some people, this settles down over time. For others, it persists.
Blood thinners can also extend bleeding duration because they slow your body’s ability to form clots and stop the flow. Hormonal birth control methods, including the pill, the patch, or hormonal IUDs, sometimes cause prolonged spotting or breakthrough bleeding when you first start them or switch formulations. This typically resolves within three to six months as your body adjusts.
Bleeding Disorders
Sometimes the issue isn’t in the uterus at all. It’s in the blood itself. Von Willebrand disease is an inherited condition where the blood lacks enough of a specific protein needed for proper clotting. Among women with chronic heavy menstrual bleeding, the prevalence of von Willebrand disease ranges from 5% to 24%, making it far more common than most people realize.
Clues that a bleeding disorder might be involved include heavy periods that started from your very first cycle, a history of nosebleeds or easy bruising, prolonged bleeding after dental work or surgery, or a family history of bleeding problems. If your doctor suspects a clotting issue, blood tests can measure the specific proteins involved.
Why It Matters: Iron and Energy
A period that runs long every month doesn’t just disrupt your schedule. It steadily depletes your iron stores. Your body uses iron to make hemoglobin, the molecule in red blood cells that carries oxygen. Lose too much blood, and your iron drops below what your diet can replace.
Iron deficiency shows up as exhaustion that sleep doesn’t fix, brain fog, dizziness, shortness of breath during normal activity, and feeling cold when others are comfortable. A ferritin level (your stored iron) below 30 nanograms per milliliter indicates deficiency, and hemoglobin below 12 grams per deciliter means you’ve crossed into anemia. Many people with long, heavy periods live with these symptoms for years, assuming they’re just tired, when the real problem is blood loss they’ve normalized.
How Doctors Figure Out the Cause
The first step is usually blood work to check your hormone levels, thyroid function, iron stores, and clotting ability. From there, imaging and procedures narrow down structural causes:
- Ultrasound uses sound waves to create pictures of your uterus and ovaries, and can identify fibroids, polyps, or other abnormalities.
- Sonohysterography involves injecting fluid into the uterus during an ultrasound to get a clearer view of the lining.
- Hysteroscopy uses a thin, lighted instrument inserted through the cervix to let a doctor see the inside of the uterus directly.
- Endometrial biopsy takes a small tissue sample from the uterine lining to check for precancerous changes or other abnormalities.
Not everyone needs all of these. Your doctor will typically start with an ultrasound and blood work, then move to more detailed tests if the picture is still unclear.
Treatment Options
Treatment depends on the cause, but several effective options exist even before a specific diagnosis is pinned down.
Hormonal treatments are the most common first step. Birth control pills, hormonal IUDs, or progesterone therapy can thin the uterine lining and regulate the cycle, often shortening periods significantly. For people whose long periods stem from hormonal imbalance, this can resolve the problem entirely.
For those who prefer non-hormonal options, tranexamic acid is a medication that helps blood clot more effectively. In a randomized trial, women taking it saw their menstrual blood loss drop by about 40%, compared to just 8% with a placebo. Roughly 43% of treated cycles fell below the heavy-bleeding threshold, versus 17% of cycles on placebo. It’s taken only during your period, for up to five days per cycle, so it’s not a daily medication. Anti-inflammatory pain relievers like ibuprofen can also modestly reduce flow by affecting the compounds that trigger uterine contractions.
If fibroids or polyps are the cause, removing them often resolves the bleeding. This can range from a minimally invasive procedure done through the cervix to surgical options for larger growths. For people who are done having children and haven’t responded to other treatments, procedures that remove or ablate the uterine lining are also an option.
Signs That Need Prompt Attention
Most causes of prolonged periods are manageable, but certain patterns warrant faster evaluation. Soaking through at least one pad or tampon per hour for more than two consecutive hours is a sign of acute heavy bleeding that needs medical attention soon, not at your next annual exam. The same goes for any vaginal bleeding after menopause, bleeding that starts suddenly between periods with no prior history of it, or passing large clots consistently throughout your period. These don’t necessarily mean something dangerous is happening, but they do mean the cause should be identified rather than waited out.