The red flags

What it is

Periods vary from person to person, and some discomfort is common. But common isn't the same as normal. Some patterns are the body's way of saying something needs a look, and many people live with them for years because no one told them otherwise.

In a 2025 UK survey, people with heavy or painful periods waited 22 months on average between symptoms starting and first seeing a medical professional.¹ Only 1 in 10 women could name every sign of heavy bleeding.¹ In a large French study, endometriosis took 10 years on average to diagnose.²

Myth: Bad period pain is just part of being a woman.

Many of us were told this by people who loved us and were told the same thing themselves. More than half of people who menstruate have some pain for a day or two, and it's usually mild. For some, it's severe enough to stop normal life for several days a month. Pain like that, or pain that pain relievers don't ease, can come from a condition such as endometriosis, fibroids or adenomyosis, and finding the cause is the next step.³ Saying so isn't overreacting.

The red flags

ACOG, the US group of OB-GYNs, counts these as abnormal bleeding:⁴

• bleeding or spotting between periods
• bleeding or spotting after sex
• a period that lasts more than 7 days
• cycles shorter than 21 days or longer than 35 days
• cycles that change in length by more than 7 to 9 days from one to the next
• no period for 3 to 6 months (when not pregnant)
• any bleeding after menopause

These are signs of heavy bleeding:⁵

• soaking through one or more pads or tampons every hour for several hours in a row
• needing two pads at once, or to change during the night
• clots the size of a quarter or larger

And these are signs that pain needs a doctor:³

• it keeps you from school, work or daily activities
• it gets worse over time, starts days before a period, or doesn't go away after it ends
• pain relievers like ibuprofen don't help

What could be behind it

Many things can cause unusual bleeding, and sometimes there is more than one. Common ones include:⁴

• Problems with ovulation, which are common in the first years of periods and around perimenopause, and happen with conditions like PMOS and thyroid disease
• Fibroids and polyps, noncancerous growths in or on the uterus
• Adenomyosis and endometriosis
• A bleeding disorder, such as von Willebrand disease
• Medicines and devices, including blood thinners, hormonal birth control and the copper IUD
• Pregnancy-related causes, such as miscarriage or ectopic pregnancy
• Infections, such as pelvic inflammatory disease
• Cancer, rarely. Unusual bleeding can be an early sign of endometrial cancer, which mostly affects people in their mid-60s after menopause and is usually found early, when treatment works best.⁴

The next lessons cover these one by one.

Get ready for the visit

Write down, for a few cycles, the dates each period starts, how many days it lasts, and how heavy it is each day (spotting, light, medium or heavy). A calendar or an app works.⁴ Bring a list of medicines, including ones bought without a prescription, and your birth control method.⁴

Get care now: if you're soaking a pad or tampon every hour for more than 2 hours in a row and you also have chest pain, shortness of breath, or feel lightheaded or dizzy, get emergency care right away.⁴