If You Have This Blood Type, Your Risk of a Blood Clot Skyrockets

Are you at heightened risk of this frightening condition?

Blood clots are not inherently dangerous; our blood is designed to clot, so that when we're injured, we won't bleed to death. However, when a blood clot makes its way to your heart, lung, or brain, it can be lethal. A pulmonary embolism (PE), for example, is a blood clot that forms in your body—often your leg—and travels to an artery in your lungs, blocking blood flow, say the experts at Johns Hopkins Medicine. PE can quickly become life-threatening, and is therefore always an emergency situation.

Risk factors for pulmonary embolism and other dangerous types of blood clots include a family history of blood clotting disorders, being on extended periods of bed rest, pregnancy, smoking, and obesity. But one other thing may increase your risk of a dangerous blood clot, according to an April 2021 study done in Sweden. People with one blood type in particular may be at higher risk of developing a blood clot, they say. Read on to find out what it is, and how to lower your risk no matter what blood type you have.

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Your blood type is inherited genetically.

image of a family tree
tomertu / Shutterstock

Not sure what your blood type is? Your parents' blood type may provide a clue. That's because your blood type is inherited from them, passed down genetically, says Penn Medicine. Determined by proteins in your red blood cells called antigens, there are four main blood types: A, B, AB, and O. The Rhesus, or Rh, factor, may be either positive or negative for each type, meaning there are eight possible blood types. Thirty-seven percent of the population has O+ blood, making it the most common type (and the highest in demand at blood banks), according to the American Red Cross.

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Researchers recently discovered a new blood type.

A closeup of a doctor's hand reaching for a blood sample in a vial

While it's true that blood types generally fall into one of the eight categories previously mentioned, scientists said this month that they've discovered a new group of blood types. Per CNN, a study published in the journal Blood described a blood type called the "Er blood group," which can cause immune cells to attack other cells. "The Er antigen was discovered years ago, but the study is the first to describe different mutations of the antigen," they reported. While this blood type is rare, researchers say it could be important for healthcare providers to be aware of "if they are having trouble diagnosing their patient."

People with this blood type may be at higher risk of blood clotting problems.

Person with pain in calf

A Swedish study, published in the April 2021 issue of the journal eLife, looked at the link between blood type and over a thousand different diseases and found that people with type A blood were more likely to develop PE and portal vein thrombosis (PVT)—another potentially deadly type of blood clot. PVT is especially scary because, as Healthline reports, it often has no symptoms. "Although PVT is treatable, it can be life-threatening," they write, adding that the risk factors for PVT include liver disease, inflammation of the pancreas, appendicitis, and trauma or injury.

One in three people have A+ blood, the American Red Cross says, while one in 16 have A- blood, making type A blood overall one of the more common blood types.

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Doing these things can help reduce your risk of a blood clot.

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iStock / kate_sept2004

While the idea of developing a blood clot is scary, you can take action to lower your risk—no matter what your blood type is. Verywell health says the most important thing you can do to reduce your chance of a life-threatening blood clot is to stop using tobacco products, if you're in the habit. Other lifestyle changes you can make include getting plenty of exercise—walking counts!—as well as maintaining a healthy weight, eating less salt, and taking your medications as prescribed.

Speak with your healthcare provider if you're concerned about blood clots, and to find out whether you're at risk due to your blood type or other factors. If you don't know your blood type, you can also ask them to tell you, or to test you if it's not already part of your medical record.

Elizabeth Laura Nelson
Elizabeth Laura Nelson is the Deputy Health Editor at Best Life. A mom and a marathon runner, she’s passionate about all aspects of health and wellness. Read more