Heavy periods and anemia

What it is

Heavy menstrual bleeding is very common: about a third of women seek treatment for it. It is not normal, and it can be a sign of a health problem that needs treatment.¹ It is also common in teens, among whom it affects an estimated 34 to 37%.²

Many people don't know their bleeding counts as heavy, especially if everyone in their family bleeds the same way. In a 2025 UK survey, only 1 in 10 women could name all the signs.³

The signs

Any of these can mean bleeding is heavy:¹

• bleeding that lasts more than 7 days
• soaking through one or more pads or tampons every hour for several hours in a row
• needing to wear more than one pad at a time
• needing to change during the night
• clots as big as a quarter or larger

Why it matters: iron

Blood carries iron. Losing a lot of blood every month can use up the body's iron stores and lead to iron-deficiency anemia, when there aren't enough healthy red blood cells to carry oxygen around the body.¹ Heavy periods are one of the most common causes.⁴

Signs of anemia include:⁴

• tiredness and lack of energy
• shortness of breath
• headaches
• a racing or pounding heart
• paler skin than usual

Severe anemia can cause shortness of breath and raise the risk of heart problems.¹ A blood test called a complete blood count (CBC) can show anemia.⁵ Iron-rich foods include meat, beans and lentils, dark green leafy vegetables, dried fruit, and fortified cereals and bread.⁴

When it's a bleeding disorder

Some heavy periods happen because the blood doesn't clot properly. The most common inherited bleeding disorder, von Willebrand disease, affects up to 1% of people in the US.⁶ Women who have it can wait a long time for an answer: in one CDC study, women waited 16 years on average between their first bleeding symptoms and a diagnosis.⁷

Signs to mention to a doctor:^5,6

• heavy periods since the very first one
• heavy bleeding after childbirth, surgery or dental work
• bruises bigger than a quarter, often
• nosebleeds five or more times a year
• a family member with a bleeding disorder

What else can cause it

Fibroids and polyps, adenomyosis, endometriosis, irregular ovulation (common in the teen years, around perimenopause, and with PMOS or an underactive thyroid), blood thinners, the copper IUD, pregnancy-related problems and infections can all cause heavy bleeding. Rarely, it's an early sign of endometrial cancer.¹ Sometimes no cause is found.¹

Treatment depends on the cause, and there are many options. See ACOG's guide to heavy menstrual bleeding for what doctors may suggest.

When to see a doctor

See a doctor if your bleeding matches any of the signs above, or if you feel tired, dizzy or short of breath during or after your period. Track the dates and how heavy each day is before you go.¹

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.⁵