A period that lasts longer than 7 days is generally considered too long. Most periods last between 3 and 7 days, with the heaviest flow typically occurring in the first 2 to 3 days before tapering off. If your bleeding regularly extends past that 7-day mark, or if a period that was once shorter has started stretching longer, something may be driving the change.
What Counts as a Normal Period
A typical menstrual cycle runs 21 to 35 days from the first day of one period to the first day of the next. Within that cycle, the bleeding phase itself averages 3 to 5 days, though up to 7 days still falls within normal range. Total blood loss for a whole period is usually 30 to 40 milliliters, roughly 2 to 3 tablespoons. Anything over 80 milliliters (about 16 fully soaked regular pads or tampons across the entire period) is classified as very heavy flow.
Of course, nobody measures their blood loss in milliliters. A more practical way to gauge whether your flow is too heavy: if you’re soaking through a pad or tampon every hour for several consecutive hours, that’s abnormal. Passing blood clots the size of a quarter or larger is another sign the CDC flags as a concern. Needing to double up on protection or waking at night specifically to change a pad also suggests your bleeding has crossed past what’s typical.
Why a Period Might Last Too Long
Prolonged periods can stem from structural problems in the uterus or from hormonal and systemic issues that don’t show up on an image. Doctors organize these causes into two broad groups.
Structural causes include uterine polyps (small growths on the uterine lining), adenomyosis (where the lining tissue grows into the muscular wall of the uterus), fibroids (noncancerous muscular growths), and, less commonly, precancerous or cancerous changes in the uterine lining. These can physically prevent the uterus from contracting efficiently to stop bleeding, or they can increase the surface area of tissue that sheds each cycle.
Non-structural causes cover a wider range. Ovulatory dysfunction, where your body doesn’t release an egg regularly, is one of the most common. Without ovulation, hormone levels don’t follow their normal pattern, and the uterine lining can build up unevenly and shed unpredictably. Thyroid disorders, blood clotting problems, and certain medications (particularly blood thinners and some types of hormonal contraception) can also extend bleeding. Even an IUD, while effective for contraception, can cause longer or heavier periods in the first several months after insertion, particularly the copper type.
How Perimenopause Changes the Rules
If you’re in your 40s and your periods are suddenly longer or less predictable, perimenopause is a likely factor. During early perimenopause, cycles that vary by 7 or more days from your usual pattern are a hallmark sign. In late perimenopause, you may go 60 or more days between periods, and when bleeding does arrive, it can be heavier or last longer than what you were used to in your 30s.
That said, perimenopause doesn’t get a free pass for all bleeding changes. Even during this transition, bleeding that lasts longer than 7 days, bleeding between periods, or periods that come closer than 21 days apart warrant a closer look. These can signal fibroids, polyps, or endometrial changes that become more common with age and shouldn’t be written off as “just perimenopause.”
When Long Periods Become a Health Problem
The most common downstream risk of chronically long or heavy periods is iron deficiency anemia. Your body uses iron to make the hemoglobin in red blood cells, and when you lose more blood each month than your body can easily replace, iron stores drop. The symptoms creep up gradually: fatigue that doesn’t improve with sleep, feeling short of breath during normal activity, dizziness, pale skin, and cold hands and feet. Many people adapt to these symptoms over months or years without realizing the cause.
More acute warning signs include feeling lightheaded or faint during your period, a racing heartbeat at rest, or bleeding so heavy that it interferes with daily activities. If you’re soaking through pads hourly and feeling dizzy or weak, that combination calls for prompt medical attention rather than waiting for a scheduled appointment.
What a Workup Looks Like
If you bring up prolonged periods with your doctor, expect them to start with questions: how long your periods last, how heavy the flow is, whether you pass clots, and whether the pattern has changed recently. Keeping a simple log for a cycle or two, noting which days you bleed and how many pads or tampons you use, gives your provider much more useful information than a vague description.
Blood work is typically the first test. This checks for iron deficiency anemia, thyroid problems, and clotting disorders, all of which can drive prolonged bleeding. A pelvic ultrasound uses sound waves to look at the uterus and ovaries for structural issues like fibroids or polyps. If the ultrasound suggests something on the uterine lining, a sonohysterogram (where fluid is injected into the uterus to get a clearer picture) or a hysteroscopy (where a thin camera is passed through the cervix to view the inside directly) may follow.
For anyone over 35 with abnormal bleeding, or younger people with certain risk factors, an endometrial biopsy is common. A small tissue sample from the uterine lining is checked for precancerous or cancerous cell changes. The procedure is quick and done in a regular office visit, though it can cause cramping similar to a strong period cramp for a minute or two.
Tracking What Matters
Before assuming something is wrong, it helps to know what your actual pattern looks like. Many people overestimate or underestimate their flow because they’ve never tracked it precisely. For two to three cycles, note the start and end dates of bleeding, the number of pads or tampons you fully soak each day, any clots and their approximate size, and any symptoms like fatigue, dizziness, or pain.
This information does two things. It tells you whether your period genuinely exceeds 7 days or just feels long because of spotting at the tail end (light spotting on days 6 and 7 is different from full-flow bleeding on day 9). And if you do need medical evaluation, a concrete log gives your provider far better data to work with than relying on memory alone.