Mayo Clinic Health Library

Question

Blood clots during menstruation: A concern?

Is it normal to pass large blood clots during menstruation?

Updated: 03-01-2013

Answer

Passing blood clots during menstruation can be normal. The amount, length and frequency of menstrual bleeding vary from woman to woman.

However, passing large blood clots may be a sign that something's not right. If your periods seem heavier than usual — for instance, soaking through one pad or tampon every hour for several hours, passing large blood clots, or passing many smaller blood clots in a short time — check with your doctor.

Your doctor can determine if there's an underlying problem causing your heavy periods. Your doctor may also recommend a blood test to check for anemia, a blood condition that can cause you to feel weak or tired.