Recent Blog Articles
Talking to your doctor about your LGBTQ+ sex life
Untangling grief: Living beyond a great loss
Thunderstorm asthma: Bad weather, allergies, and asthma attacks
Heart problems and the heat: What to know and do
I’m too young to have Alzheimer’s disease or dementia, right?
Period equity: What it is and why it matters
Back pain: Will treatment for the mind, body—or both—help?
Colon cancer screening decisions: What’s the best option and when?
Cognitive effects in midlife of long-term cannabis use
If climate change keeps you up at night, here's how to cope
Heavy Menstrual Periods
Many women feel that their periods are heavy. Doctors consider a woman's menstrual periods to be genuinely "heavy" when they meet any one of three criteria:
periods last eight days or longer
the blood flow causes you to change your sanitary napkin or tampon more than once an hour for six hours in a row or longer
there is a significant increase in the amount or number of days of your usual flow, compared with your own usual periods.
It's normal for menstrual flow and duration to vary somewhat from period to period. If you have a repeated, long-lasting increase in monthly flow then you should be evaluated by a doctor. About ten percent of women have heavy periods, also called "menorrhagia." Some of the more common causes include hormone changes, thyroid problems, growths or other changes in the uterus, problems with your blood's ability to clot, or a pelvic infection.
Heavy periods usually keep to the monthly cycle pattern. Sometimes bleeding can last or recur throughout the month and it may be hard to know when one period ends and another begins, a problem known as "menometrorrhagia." If your bleeding is not occurring in a clear monthly cycle, please visit our health guide on Bleeding Between Menstrual Periods.
The Heavy Menstrual Periods Decision Guide is designed to give you some information about what may cause monthly periods to be heavy and what steps you can take to get help. This guide is not meant to substitute for a doctor's evaluation.
Very heavy bleeding can be an emergency. You might need an urgent evaluation by your doctor.
Are your menstrual periods lasting eight or more days, or are you bleeding so much that you change pads or tampons more than once an hour?
To continue reading this article, you must log in.
Subscribe to Harvard Health Online for immediate access to health news and information from Harvard Medical School.
- Research health conditions
- Check your symptoms
- Prepare for a doctor's visit or test
- Find the best treatments and procedures for you
- Explore options for better nutrition and exercise
I'd like to receive access to Harvard Health Online for only $4.99 a month.Sign Me Up
Already a member? Login ».
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles.
No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
Free Healthbeat Signup
Get the latest in health news delivered to your inbox!