A normal period lasts about 4 to 5 days, and anything that stretches beyond 7 days is considered prolonged. If your period has been dragging on longer than usual, several things could be behind it, from hormonal shifts and new medications to structural changes in the uterus. Most causes are treatable once identified.
What Counts as a Long Period
The CDC defines normal menstrual bleeding as roughly 4 to 5 days, with about 2 to 3 tablespoons of total blood loss. Bleeding that lasts more than 7 days qualifies as heavy menstrual bleeding, also called menorrhagia. But even if your period has gone from 4 days to 6 or 7, that shift is worth paying attention to, especially if it happens repeatedly or comes with heavier flow than you’re used to.
Hormonal Changes and Perimenopause
Hormones are the most common reason periods change in length, and the shift doesn’t always happen dramatically. Estrogen and progesterone regulate how thick your uterine lining grows each month and when it sheds. When those hormones fluctuate, the lining can build up more than usual, which means more tissue to shed and a longer bleed.
Perimenopause is a major trigger. Most women notice changes in their 40s, but some experience them as early as their 30s or as late as their 50s. During this transition, estrogen and progesterone rise and fall unpredictably. You may skip ovulation some months, which allows the uterine lining to keep thickening without the hormonal signal to stop. When your period finally arrives, it can be heavier, longer, or both. The time between periods may also become erratic, with cycles getting shorter or longer without a clear pattern.
Thyroid disorders and polycystic ovary syndrome (PCOS) can also throw off hormone levels enough to change your cycle. If your periods have shifted alongside symptoms like unexplained weight changes, fatigue, or acne, a hormonal issue may be the root cause.
Fibroids and Polyps
Growths inside or on the uterus are a common structural cause of longer periods. Uterine fibroids are noncancerous muscle tumors that can range from the size of a seed to the size of a grapefruit. They increase the surface area of the uterine lining, which means more tissue builds up and more blood is lost during your period. Larger fibroids can also physically interfere with the uterus’s ability to contract and stop bleeding efficiently.
Uterine polyps are smaller, finger-like growths on the inner wall of the uterus. They’re estrogen-sensitive, meaning they grow in response to the estrogen your body produces. Polyps can cause irregular bleeding, unpredictable periods that vary in length and heaviness, and spotting between cycles. Both fibroids and polyps are typically found through an ultrasound and are treatable with minor procedures when they’re causing problems.
Medications That Extend Bleeding
If you recently started a new medication and your period got longer, the two may be connected. Blood thinners (anticoagulants) are one of the most well-documented culprits. These medications work by interrupting the body’s clot-forming process, which is exactly what your uterus relies on to slow and stop menstrual bleeding. Premenopausal women on anticoagulants are at higher risk for heavier and longer periods.
Certain antidepressants, particularly SSRIs, can also affect bleeding patterns. And aspirin, even at low daily doses for heart health, thins the blood enough to extend period length in some women.
IUDs and Birth Control
The copper IUD is well known for making periods longer and heavier, especially in the first few months after insertion. Because it contains no hormones, it doesn’t thin the uterine lining the way hormonal methods do. Many women report irregular bleeding for several months after getting one. These side effects typically ease up within three to six months, but for some women, heavier and longer periods persist for as long as the device is in place.
Switching hormonal birth control methods can also temporarily disrupt your cycle. Going off the pill, changing to a new formulation, or starting or stopping hormonal IUDs and implants can all cause a transition period where bleeding is unpredictable. Your body generally adjusts within a few cycles, but prolonged changes are worth mentioning to your provider.
Bleeding Disorders
About 13% of women with heavy menstrual bleeding turn out to have an underlying bleeding disorder, with von Willebrand disease being the most common. This condition affects the blood’s ability to clot properly, which makes it harder for the uterus to stop bleeding once a period starts. Some studies put the prevalence as high as 20% among women referred to specialty clinics for heavy periods.
If your periods have always been long and heavy since they first started, you bruise easily, or you’ve had prolonged bleeding after dental work or surgery, a bleeding disorder is worth investigating. A simple blood test can screen for it, and it often runs in families.
Signs Your Bleeding Needs Attention
A period that runs a day or two longer than usual once or twice isn’t necessarily alarming. But certain patterns signal something that shouldn’t wait. Watch for these:
- Soaking through a pad or tampon every hour for more than two consecutive hours
- Blood clots larger than a quarter
- Needing to wake up at night to change protection
- Doubling up on pads and tampons to manage flow
- Feeling exhausted, dizzy, or short of breath, which are signs of anemia from blood loss
- Bleeding between periods or after menopause
Prolonged heavy bleeding can lead to iron-deficiency anemia over time, even if no single period feels extreme. If you’re consistently tired or winded during your period, your blood count may be low.
What to Expect at the Doctor
If you go in for prolonged periods, expect a conversation about your full medical history, including past pregnancies, surgeries, current medications, and your birth control method. A pelvic exam is standard. Your doctor will likely order a complete blood count to check for anemia and may test thyroid function and hormone levels.
An ultrasound is the most common next step if structural causes like fibroids or polyps are suspected. In some cases, a closer look at the uterine lining through a more detailed imaging procedure or a small tissue sample may be needed to rule out other causes. Keeping a record of your cycle length, flow heaviness, and any associated symptoms for two to three months before your visit gives your provider much more to work with than a general description.