Period Blood Clots: Are They Normal?

Having a period is normal. And while a menstruation cycle can vary in length, amount and frequency, menstrual blood clots can be a scary thing when you see them. Most blood clots during a period are normal, but if you experience large blood clots and notice changes in your period, it may be time to talk to a doctor.

Ob/Gyn Salena Zanotti, MD, talks with us about period clots, what they mean and when you need to be treated.

What are period clots?

During menstruation, the hormones in your body cause the lining of your uterus to begin shedding. During that process, small blood vessels bleed. To prevent your body from losing too much blood, plasma and platelets work together to form blood clots.

“Blood clots will form anytime you have a certain amount of blood that just sits there,” Dr. Zanotti says. “Blood clots are supposed to happen to some degree, like when you cut yourself. But with period clots, what happens is if you’re having a good amount of bleeding, it collects inside your uterus and as it sits there it will make a clot.”

What causes period clots?

Most menstrual blood clots are normal. At the beginning and the end of your cycle, they may appear bright red. Because your flow is moving quickly, the blood does not have time to darken. You may also see dark red or maroon clots during the first few days of your period when your flow is the heaviest.

“A woman will feel a clot if she’s been in bed or been sitting and then she stands up,” says Dr. Zanotti. “A clot will either come out then, or when she goes to the bathroom.”

Your cervix has to dilate in order to pass larger blood clots. The pain can be strong. If you have a heavy flow and experience cramping, this is partially why you have pain. 

There are many conditions that can cause someone to have abnormally large blood clots or experience a heavier flow than normal. Some include:

• Thyroid disease.
• Uterine polyps.
• Uterine fibroids.
• A bleeding disorder.
• Cancer in your uterus or cervix.

Are period clots serious?

If you have heavy menstrual bleeding, it can be serious. But Dr. Zanotti says it depends on each situation. Doctors will consider the size and frequency.

“A lot of women have really small clots that might be a dime-size or Ωa quarter-size during their period and that’s normal for them,” she says. “It’s problematic if you’re passing golf ball-sized clots and passing them every couple of hours.”

You should also be concerned if you must change your pad or tampon about every hour.

“You may have heavy bleeding if you’re soaking through your pad in an hour and it happens for a couple of hours in a row,” says Dr. Zanotti. “That’s a significant amount of bleeding.”

It’s also possible to become anemic or have low blood pressure after losing too much blood, says Dr. Zanotti.

“If heavy bleeding happens once during a cycle and it’s not repetitive, that’s not so concerning,” she says. “You have to look at the pattern of how frequently it’s happening and how long it’s actually lasting.”

If you’re pregnant and experience blood clots, contact your doctor or go to the nearest emergency room. You may be having a miscarriage or an ectopic pregnancy, which can be life-threatening.

When to see a doctor

Period blood clots are a normal part of your menstrual cycle. But when you notice any changes to the size and amount, it could point to an underlying condition. When speaking to your doctor, be prepared with the following information:

• How long your period usually lasts.
• How heavy your usual flow is.
• If you’ve been bleeding between periods.
• If you’ve noticed changes over time.
• If you’ve been experiencing pain.
• If there’s a chance you might be pregnant.
• A list of medications you are currently on.
• A list of other medical conditions.

Expect your doctor to do a pelvic exam. They may also want to do a blood test, a pap test or an ultrasound during your visit.

After an exam and testing, your doctor may prescribe the following based on the results, how severe the clots are and your other symptoms:

• Contraceptives (birth control).
• Non-steroidal anti-inflammatory drugs (NSAIDs).
• Tranexamic acid.
• Hormonal therapy.
• Antifibrinolytic medicine.
• Surgery.

Overall, Dr. Zanotti says if you’re concerned about whether blood clots are normal during your period, you should discuss it with your healthcare provider. “Sometimes women just need reassurance about what they’re dealing with — that it may be OK and there’s nothing wrong,” she says. “It can be very common, and it can be managed. Women don’t need to suffer and it’s nothing to be embarrassed about.”