A heavy period usually means your body is producing too much uterine lining, not shedding it efficiently, or both. Normal menstrual bleeding lasts about four to five days and totals around two to three tablespoons of blood. If you’re soaking through a pad or tampon every one to two hours, passing clots larger than a quarter, or bleeding for more than seven days, your period qualifies as abnormally heavy, and there’s almost always an identifiable reason.
How to Tell If Your Bleeding Is Actually Heavy
It’s easy to assume your period is just “your normal,” especially if it’s always been heavy. But certain signs point to blood loss that goes beyond typical variation. Needing to change your pad or tampon after less than two hours, doubling up on protection (pad plus tampon), or waking up at night specifically to change are all red flags. Clots the size of a quarter or larger are another clear signal.
Women with heavy menstrual bleeding typically lose roughly twice the normal amount of blood and bleed for more than seven days. That level of loss adds up quickly. About 75% of anemia cases are caused by iron deficiency, and chronic heavy periods are one of the most common drivers. If you’re feeling unusually fatigued, dizzy, short of breath during mild activity, or having trouble concentrating, your period may already be affecting your iron levels.
Hormonal Imbalance and Skipped Ovulation
The most common reason for a heavy period is a hormonal one. In a typical cycle, estrogen builds up the uterine lining during the first half, then progesterone stabilizes it after ovulation and triggers shedding when levels drop. If you don’t ovulate in a given cycle, progesterone never enters the picture. Your lining keeps thickening under estrogen’s influence with no signal to stop, and when it finally sheds, the result is a heavier, longer, and often unpredictable bleed.
This happens occasionally to most people, especially during stress, illness, or major weight changes. But for some, skipped ovulation is chronic. When the lining builds unchecked over weeks or months, it can become abnormally thick, a condition called endometrial hyperplasia. That overgrown lining causes heavy, prolonged bleeding and, in some cases, bleeding between periods or cycles shorter than 21 days.
PCOS and Irregular Cycles
Polycystic ovary syndrome is one of the most common reasons people don’t ovulate regularly. The classic pattern with PCOS is periods spaced more than 35 days apart, sometimes much longer. You might go weeks or months with no period at all, and then suddenly have an extremely heavy one. That heavy bleed happens because the lining has been accumulating the entire time without the progesterone-driven shedding that a regular cycle provides. The longer the gap between periods, the heavier the eventual bleed tends to be.
Fibroids and Adenomyosis
Uterine fibroids are noncancerous growths in or on the uterine wall. They’re extremely common, particularly after age 30, and the ones that grow near the inner lining of the uterus are the most likely to cause heavy bleeding. They distort the uterine cavity, increase the surface area that bleeds, and can interfere with the uterus’s ability to contract and stop blood flow after shedding.
Adenomyosis is a related but distinct condition where tissue that normally lines the uterus grows into the muscular wall instead. It causes the uterus to enlarge and take on a rounded, “boggy” shape. Heavy menstrual bleeding occurs in 40% to 60% of people with adenomyosis, driven by the increased surface area of the lining and greater blood supply to the affected tissue. The bleeding correlates directly with how deeply the tissue invades the muscle wall.
These two conditions can coexist, and distinguishing them matters because the treatments differ. Adenomyosis tends to cause more painful periods, pain during sex, and chronic pelvic pain than fibroids alone. When someone with known fibroids has significant pain on top of heavy bleeding, adenomyosis is often the missing piece. An MRI can differentiate between the two with about 89% accuracy, which is better than ultrasound for this specific question.
Bleeding Disorders You May Not Know About
Not all heavy periods come from the uterus itself. Between 5% and 24% of women with chronic heavy menstrual bleeding turn out to have von Willebrand disease, a genetic condition that impairs the blood’s ability to clot. That’s a surprisingly high number for a disorder most people have never heard of. Prevalence varies by background: roughly 16% of white women with heavy periods carry the condition, compared to about 1% of Black women.
Von Willebrand disease often goes undiagnosed because heavy periods get normalized, both by the person experiencing them and sometimes by their doctors. If you’ve had heavy periods since your very first cycle, bruise easily, bleed a long time after dental work or minor cuts, or have a family history of bleeding problems, a clotting disorder is worth investigating. A simple blood test can identify it.
Other Causes Worth Knowing
Thyroid disorders, particularly an underactive thyroid, can disrupt ovulation and lead to heavier periods. Certain IUDs (copper, not hormonal) are well known for increasing menstrual flow, especially in the first several months. Endometrial polyps, which are small growths on the uterine lining, can cause heavy or irregular bleeding and are typically found on ultrasound. Less commonly, medications that thin the blood or interfere with clotting can make periods significantly heavier.
What Happens During Evaluation
The first step is usually a pelvic ultrasound to look for structural causes like fibroids, polyps, or signs of adenomyosis. Blood work checks for anemia, iron levels, thyroid function, and sometimes clotting factors. If the ultrasound is inconclusive or adenomyosis is suspected, an MRI provides a clearer picture. In some cases, a small sample of the uterine lining is taken to rule out hyperplasia or other changes.
The evaluation matters because the treatment depends entirely on the cause. A hormonal issue and a structural one require very different approaches, and many people with heavy periods have more than one contributing factor.
How Heavy Periods Are Treated
For hormonally driven heavy bleeding, the most effective option is a hormonal IUD that releases a small amount of progestin directly into the uterus. This type of IUD reduces menstrual blood loss by 80% to 95%, making it more effective than any other medication for this purpose. Many people see their periods become very light or stop entirely within a few months. It works by keeping the uterine lining thin, which means less tissue to shed each cycle.
Other hormonal options include birth control pills, which regulate the cycle and reduce flow, and oral progestin taken during specific days of the cycle. These are less effective than the IUD but still significantly reduce bleeding for most people.
For fibroids or polyps causing the problem, the approach depends on size, location, and how much they’re affecting quality of life. Options range from medications that shrink fibroids to procedures that remove them while preserving the uterus. Adenomyosis is trickier to treat surgically because the abnormal tissue is woven into the muscle wall, which is why hormonal management (particularly the hormonal IUD) is often the first-line approach.
If iron deficiency anemia has already developed, iron supplementation can reverse the fatigue, brain fog, and weakness, but it takes time. Most people need several months of consistent supplementation to rebuild their stores, and the underlying bleeding needs to be addressed simultaneously or the deficit just returns.