Prolonged or unexpected bleeding has many possible causes, and the answer depends on your specific situation: whether you’re on your period, recently gave birth, started a new birth control, or are bleeding when you shouldn’t be at all. A normal period lasts about 4 to 5 days with roughly 2 to 3 tablespoons of total blood loss. Bleeding that continues beyond 7 days, or that shows up between periods, signals something worth investigating.
Your Period Won’t Stop
Periods lasting longer than 7 days are classified as heavy menstrual bleeding. If yours regularly stretches past that mark, or you’re soaking through a tampon or pad every hour for several consecutive hours, something is driving the excess. The causes fall into a few broad categories: structural growths in the uterus, hormonal imbalances, blood clotting problems, or side effects from medications or contraception.
Heavy periods aren’t just inconvenient. Over time, losing that much blood can lead to iron-deficiency anemia, which causes fatigue, dizziness, and shortness of breath. If your bleeding is consistently heavy cycle after cycle, that’s reason enough to get evaluated rather than assuming it’s just how your body works.
Fibroids and Polyps
Uterine fibroids are noncancerous growths made of muscle and tissue that form in or on the wall of the uterus. They’re remarkably common: roughly 40% to 80% of people with a uterus develop them. Fibroids can cause heavy, irregular bleeding during your period and spotting between periods. They do this by increasing the surface area of the uterine lining, distorting blood vessels, or interfering with the uterus’s ability to contract and stop bleeding naturally.
Uterine polyps work similarly. These are small, soft growths on the inner lining of the uterus that can cause irregular or prolonged bleeding. Both fibroids and polyps are typically found through an ultrasound, and treatment ranges from monitoring to medication to surgical removal depending on size, symptoms, and whether you want to preserve fertility.
Hormonal Imbalances
Your menstrual cycle depends on a precise rise and fall of hormones. When that balance is off, the uterine lining can build up too much before shedding, leading to heavier or longer bleeding. Two of the most common hormonal culprits are polycystic ovary syndrome (PCOS) and thyroid problems.
With PCOS, ovulation doesn’t happen regularly. Without ovulation, progesterone (the hormone that triggers a clean, timely shedding of the lining) never kicks in. Estrogen continues building the lining unopposed, and when it finally breaks down, the bleeding is heavier and more unpredictable. Hypothyroidism, or an underactive thyroid, can cause the same pattern. The thyroid influences how your reproductive hormones behave, and when it’s sluggish, anovulation and prolonged bleeding often follow.
Both conditions are diagnosable through blood work. If your periods have always been irregular or have recently become unpredictable, a hormone panel and thyroid check are reasonable first steps.
Breakthrough Bleeding on Birth Control
If you recently started hormonal birth control, unexpected bleeding is one of the most common side effects during the adjustment period. With hormonal IUDs, spotting and irregular bleeding in the first few months is normal and usually improves within 2 to 6 months. The pill follows a similar pattern, with most users seeing stabilization after 2 to 3 months.
The implant is a different story. With the implant, the bleeding pattern you experience in the first 3 months tends to be your pattern going forward. So if you’re still having frequent or prolonged bleeding after that initial window, it’s less likely to resolve on its own and worth discussing with your provider.
Missing pills, taking them at inconsistent times, or interactions with other medications can also trigger breakthrough bleeding. If you’ve been on the same method for a while and suddenly start bleeding again, that’s a separate issue from the normal adjustment phase and may point to something else going on.
Pregnancy-Related Bleeding
Bleeding that you assume is a period could sometimes be pregnancy-related. Early miscarriage is one of the most common causes of unexpected heavy bleeding, and it can closely mimic 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 presents first as light vaginal bleeding paired with pelvic pain. If blood leaks from the fallopian tube, you may also feel shoulder pain or pressure like you need to have a bowel movement. This is a medical emergency. Severe abdominal or pelvic pain with vaginal bleeding, extreme lightheadedness, or fainting requires immediate care.
If there’s any chance you could be pregnant and you’re experiencing unexpected bleeding, a pregnancy test is the fastest way to rule this in or out.
Blood Clotting Disorders
Some people bleed heavily because their blood doesn’t clot properly. Von Willebrand disease is the most common inherited bleeding disorder, and it often goes undiagnosed for years because people assume their heavy periods are just normal for them. Among women with chronic heavy menstrual bleeding, between 5% and 24% have von Willebrand disease.
Clues that a clotting disorder might be behind your bleeding include heavy periods that started when you first began menstruating, a history of prolonged bleeding after dental work or surgery, easy bruising, or frequent nosebleeds. If heavy periods run in your family or your bleeding has never responded to typical treatments, screening for a bleeding disorder is worth pursuing.
Postpartum Bleeding That Won’t Quit
If you recently gave birth, bleeding for weeks afterward is expected. This discharge, called lochia, follows a predictable progression. In the first 3 to 4 days, it’s dark or bright red with a heavy flow and small clots. From roughly day 4 through day 12, it shifts to a pinkish-brown, more watery discharge with fewer or no clots. Around day 10 to 14, it transitions to a creamy, yellowish-white color with light flow or spotting. This final stage can last up to 6 weeks after delivery.
What’s not normal: bleeding that suddenly gets heavier after it had started to taper, passing clots larger than a quarter, bright red bleeding returning after it had already turned pink or brown, or soaking through a pad in an hour. These can signal retained placental tissue or infection and need prompt evaluation.
How to Gauge Whether Your Bleeding Is Too Heavy
Since you can’t easily measure blood volume at home, practical signs matter more than milliliters. Your bleeding is considered heavy if you’re soaking through a pad or tampon every hour for several hours in a row, needing to double up on protection, passing clots larger than a quarter, or bleeding that restricts your normal daily activities. Needing to wake up at night to change your pad is another common indicator.
Tracking your cycle length, the number of products you use per day, and any symptoms like fatigue or dizziness gives you concrete information to bring to an appointment. Many of the conditions behind prolonged bleeding are very treatable once identified, but they rarely resolve without figuring out the underlying cause first.