A normal period produces about 30 to 40 milliliters of blood, roughly two to three tablespoons, over the course of three to seven days. When blood loss exceeds 80 milliliters per cycle, or when you’re soaking through a pad or tampon every hour for several hours straight, that crosses into what’s clinically considered heavy menstrual bleeding. Several common conditions can cause this, and most of them are treatable once identified.
How to Tell if Your Bleeding Is Actually Heavy
It’s hard to measure blood loss in milliliters at home, so practical signs matter more than exact volumes. Needing to change your pad or tampon more often than every two hours, passing blood clots larger than a quarter, bleeding through your clothes or bedding, or having periods that last longer than seven days all point toward genuinely heavy flow rather than a period that just feels heavy. If your bleeding has increased noticeably compared to your own baseline, that shift itself is worth paying attention to, even if it doesn’t check every box.
Fibroids and Polyps
Uterine fibroids are noncancerous growths in the muscular wall of the uterus, and they’re one of the most common reasons for heavy periods. They cause heavier bleeding through several overlapping mechanisms: increasing the total surface area of the uterine lining, boosting blood flow into the uterus, and interfering with the uterus’s ability to contract and squeeze blood vessels shut after shedding its lining. Fibroids that bulge into the uterine cavity (submucosal fibroids) tend to cause the most bleeding because they can ulcerate the lining directly above them.
Endometrial polyps, small tissue growths on the uterine lining, also contribute to heavy flow. Polyps contain abnormally thick-walled blood vessels, and the endometrium covering them doesn’t shed as completely during a period. That incomplete shedding can prolong bleeding and increase the total volume lost.
Hormonal Imbalances and Anovulation
Your menstrual cycle depends on a balance between estrogen and progesterone. Estrogen thickens the uterine lining in the first half of the cycle, and progesterone, released after ovulation, stabilizes it and triggers an orderly shed. When you don’t ovulate, which can happen during perimenopause, with polycystic ovary syndrome, thyroid problems, or even during periods of stress, your body never produces that progesterone signal. The lining keeps thickening under estrogen’s influence until it becomes unstable and sheds irregularly and heavily.
This pattern often shows up as periods that are unpredictable in timing and unusually heavy when they arrive. It’s especially common in teens whose cycles haven’t fully regulated and in women in their 40s approaching menopause.
Adenomyosis
Adenomyosis occurs when tissue that normally lines the inside of the uterus grows into the muscular wall. This makes the uterus enlarge and become boggy and tender. Unlike endometriosis, where similar tissue grows outside the uterus entirely, adenomyosis stays within the uterine wall itself. It causes heavy, painful periods and often a feeling of pressure or fullness in the pelvis.
Diagnosis typically starts with a transvaginal ultrasound, which can detect the characteristic changes in the uterine wall: a globular shape, areas of shadowing, and cystic changes. MRI offers higher specificity when ultrasound results are unclear. Adenomyosis is common and frequently underdiagnosed because its symptoms overlap with fibroids and other conditions.
Bleeding Disorders
An often-overlooked cause of heavy periods is an inherited bleeding disorder. Von Willebrand disease, the most common one, affects the blood’s ability to clot properly. Among women with chronic heavy menstrual bleeding, somewhere between 5% and 24% turn out to have von Willebrand disease. Many go years without a diagnosis because heavy periods are so often attributed to other causes first.
Clues that a bleeding disorder might be involved include heavy periods starting from your very first cycle, a history of easy bruising, prolonged bleeding after dental work or surgery, or a family history of bleeding problems. If these sound familiar, specific blood tests can confirm or rule out the diagnosis.
The Copper IUD
If you recently had a copper IUD placed, heavier and longer periods are a well-documented side effect. The increase in bleeding typically improves after three to six months as your uterus adjusts. If it doesn’t ease up after that window, or if the bleeding is severe enough to cause symptoms like fatigue or dizziness, it’s worth revisiting whether this contraceptive method is the right fit for you.
Why Iron Levels Matter
Chronic heavy periods drain your iron stores, and this is where heavy bleeding moves from inconvenient to medically significant. Iron deficiency develops gradually. You can have depleted iron stores well before your hemoglobin drops low enough to show up as anemia on a standard blood count. Ferritin, the protein that stores iron, is the best early indicator. Levels below 30 micrograms per liter suggest iron deficiency, and some experts use a threshold of 50.
Symptoms of low iron include fatigue that doesn’t improve with sleep, brain fog, shortness of breath during normal activity, cold hands and feet, and brittle nails. Many women with heavy periods live with these symptoms for years, assuming they’re just tired, when the real issue is that they’re losing more iron each month than their diet can replace. If you suspect this, ask specifically for a ferritin test, not just a complete blood count, since hemoglobin can remain normal even when iron stores are significantly depleted.
How Heavy Bleeding Is Diagnosed
The diagnostic workup depends on your symptoms, age, and what a physical exam reveals. A transvaginal ultrasound is often the first step and can identify fibroids, polyps, and signs of adenomyosis. If the ultrasound suggests something inside the uterine cavity, a hysteroscopy (a thin camera inserted through the cervix) gives a direct view and allows for biopsy if needed.
Endometrial biopsy is reserved for women at higher risk of abnormal cell changes: those with irregular bleeding patterns, obesity, polycystic ovary syndrome, or cases where treatment hasn’t worked. Blood work typically includes a complete blood count, ferritin, thyroid function, and sometimes clotting studies if a bleeding disorder is suspected.
Treatment Options
Treatment depends entirely on the cause, which is why getting a proper diagnosis matters before jumping to solutions. For hormonal imbalances and anovulatory cycles, hormonal options like a progestin-releasing IUD, birth control pills, or cyclical progesterone can stabilize the lining and reduce flow significantly.
For women who want a non-hormonal option, there are oral medications that help blood clot more effectively during your period. One commonly prescribed option reduces menstrual blood loss by 26% to 60% and is taken only during the days of bleeding. It works by preventing clots from breaking down too quickly once they form.
Fibroids and polyps can often be removed surgically, sometimes through minimally invasive procedures done through the cervix. Adenomyosis is trickier since it’s embedded in the uterine wall, but hormonal treatments can manage symptoms effectively for many women. In severe cases that don’t respond to other approaches, more definitive surgical options exist.
Regardless of the underlying cause, if your iron is low, replacing it with supplementation is an important parallel step. Oral iron supplements work for most people, though they can cause digestive side effects. Taking them every other day with vitamin C can improve both absorption and tolerability.