Thanks for your question! You’re right. Some clotting is normal during a woman’s period; however, sometimes there may be a medical reason that a woman has large clots. During a typical period, the body makes something called an “anti-coagulant,” which is a natural blood thinner that prevents blood from clotting. If a woman’s period is particularly heavy, or she is on the heaviest day of her period, the bleeding might be so fast that her body isn’t able to release the anti-coagulant quickly enough to keep up with the bleeding. In that case, the blood ends up clotting as it leaves the vagina.
Having some small, dark clots during your period can be normal, and often happens on a heavier flow day. However, if you are passing clots the size of a quarter or larger, or are soaking through a super tampon or pad every 1-2 hours, you are experiencing “heavy” bleeding and should make an appointment with your primary care provider or gynecologist. Heavy periods can sometimes cause a condition called anemia, which can make you feel tired and weak. If you ever feel this way, you should see your health care provider right away. Your provider will ask you questions about your menstrual cycle and may check your blood to see if you are anemic. Treatment for clotting depends on the cause of the heavy bleeding but may include medication such as birth control pills to regulate your cycle and lessen the flow. If you are anemic, your provider will also tell you to take iron pills.
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