Period blood clots: What they look like and when to see a doctor

Jelly-like period blood clots can be unnerving the first time you experience them. But they’re not necessarily something to worry about — and can just be a normal part of the menstrual cycle.

With the help of Dr. Jenna Beckham, obstetrician, gynecologist, and complex family planning specialist, WakeMed Health and Hospitals, Planned Parenthood South Atlantic, North Carolina, US, let’s explore why period blood clots form and when they might be a clue that something else could be going on. 

Key takeaways: Jelly-like blood clots during your period

• Period blood clots are may be normal for you, especially on the days when your period is heavier. 
• Size matters. Small clots (pea-sized or smaller) are typically fine, while larger ones (bigger than a bottle cap) could indicate that something else is going on and you should speak to your doctor.
• The color and texture of blood clots can vary, from dark red to brownish and from jelly-like to firmer, depending on blood flow and clotting factors.
• If you’re passing large clots regularly, experiencing severe pain, or bleeding through pads or tampons in under an hour, it’s time to talk to a doctor. 

What are period blood clots? 

Period blood clots are a more solidified version of your menstrual blood, and they’re pretty common. But “Should I worry about period blood clots?” is a health question that Dr. Beckham often gets asked in her clinic. 

Period blood clots actually form for a clever reason. You probably already know that during your period (menstruation), hormonal shifts (like fluctuations in estrogen and progesterone) cause the lining of the uterus to shed. 

“Once the lining is shed, the product of the shedding pools in the bottom of your uterus, just above or inside the cervix, waiting for your uterus to contract and allow the cervix to expel the contents,” Dr. Beckham explains. “To help break down the thickened blood and pass it more easily, the uterus also releases anticoagulants (substances that thin your shed uterine lining).  But sometimes when people have a heavier flow, the amount of bleeding can outpace the body’s ability to produce the anticoagulants, so clots form.”

Passing occasional small clots isn’t usually something to stress about. But if you’re regularly seeing large clots (bigger than a bottle cap) or have symptoms like extreme fatigue, it’s worth seeking medical advice. 

Potential causes of period blood clots

While occasional menstrual clots are normal — especially when your period is at its heaviest — certain factors can make them more frequent or larger, including:

• Hormonal changes: Fluctuations in estrogen and progesterone can impact clotting.
• Uterine fibroids or polyps: These noncancerous uterine growths can increase menstrual flow and clotting.
• Endometriosis, adenomyosis, or polycystic ovary syndrome (PCOS): These medical conditions often lead to irregular cycles with large blood clots.
• Bleeding disorders: Some medical conditions like von Willebrand disease can result in period blood clots. As can medications that interfere with blood clotting. “While it might seem like these should decrease your likelihood of forming clots, you may still see clots from the uterus because of the associated heavy bleeding,” says Dr. Beckham. 

Large, jelly-like period blood clots often go hand in hand with heavy menstrual bleeding (really heavy periods). Although heavy menstrual bleeding is common (about a third of women seek treatment for it), it isn’t something you have to put up with. There are lots of treatments that can help. 

As we mentioned above, frequent or large period blood clots can also be a sign of an underlying condition like a hormonal imbalance, polycystic ovary syndrome, fibroids, or endometriosis. If you have one of these conditions, you’ll likely have other symptoms. So it’s always worth checking in with your doctor if you’re concerned. 

Tracking your symptoms with a period app like Flo can help you figure out what’s normal for you and give you vital information to share with your doctor during your appointments. 

What do period blood clots look like? 

Period blood clots can vary in appearance, but here are some key characteristics to keep in mind.

Size and color

• Small clots (pea-sized or smaller) are common and aren’t usually a cause for concern.
• Larger clots (bigger than a bottle cap) may indicate an underlying condition. You should speak to your doctor if you see these. 
• Dark red or brownish clots typically appear when blood has taken longer to exit the body. It gets darker as it has longer to react to oxygen. 
• Bright red clots may be a sign of a heavier flow or fresher bleeding.

Consistency and texture

• Period blood clots happen when some of the small blood vessels in the lining of your uterus bleed when your uterine lining sheds during your period. Plasma and platelets work together to cause clotting to prevent you from losing too much blood. 
• They can feel a bit like jelly or semi-solid. 

Frequency 

If you’re passing clots frequently throughout your cycle or noticing a sudden increase in clotting, it may be worth looking into. Don’t be afraid to visit your doctor for a checkup. They’ll be able to help and hopefully put your mind at ease.

When should you be concerned about period blood clots?

Although jelly-like period blood clots are common and might be normal for you, it’s worth keeping a close eye on what’s going on with your period. 

“You should always discuss blood clots with your provider, just to be sure,” says Dr. Beckham. “However, don’t worry about all blood clots. It can be completely normal to pass blood clots, especially small or infrequent clots.”

There are a few signs that clotting might require medical attention though. Check in with your doctor if you experience: 

• Clots larger than a bottle cap regularly
• Bleeding through a pad or tampon in less than an hour
• Periods lasting longer than seven days
• Extreme pain that over-the-counter painkillers don’t help
• Symptoms of anemia, such as dizziness, fatigue, or shortness of breath

“Significant period pain that is not relieved with over-the-counter medications or other supportive measures like heating pads or warm baths or showers,” is another sign you should get checked out, reveals Dr. Beckham. 

Track your cycle to better manage period blood clots

If you’d like to know more about what’s typical during your period, you can use a period tracker like Flo. You can note down flow intensity and log any premenstrual syndrome symptoms. Doing this might help you understand what typical looks like for you and means you can clock any changes to your period from one month to the next.

Noticing changes in your period? If you’re concerned about clotting, pain, or heavy bleeding, don’t hesitate to reach out to your doctor. Keeping track of your symptoms can be a great first step in understanding your cycle and getting the right support.