Blood Clots


What is a blood clot?

Blood clots are gel-like collections of blood that form in your veins or arteries when blood changes from liquid to partially solid. Clotting is a normal function that stops your body from bleeding too much when you get hurt. However, blood clots that form in some places and don’t dissolve on their own can be dangerous to your health.

Normally, a blood clots start as a response to injury of a blood vessel. At first, the blood stays in one place. Two substances — platelets (a type of blood cell) and fibrin (a firm string-like substance) — combine to form what is called a platelet plug to stop up the cut or hole.

When a blood clot forms where it should not have developed, it is called a thrombus. A blood clot is also called a thrombus. The clot may stay in one spot (called thrombosis) or move through the body (called embolism or thromboembolism). The clots that move are especially dangerous. Blood clots can form in arteries (arterial clots) or veins (venous clots).

The symptoms of a blood clot, and the recommended treatment, depend on where a clot forms in your body and how much damage it could cause. Knowing the most common blood clot signs and risk factors can help you spot or even prevent this potentially life-threatening condition.

Which blood clots pose the most health risk?

Any blood clots that form in arteries (arterial clots) or veins (venous clots) can be serious. You should call your healthcare provider immediately if you suspect a blood clot.

A clot that forms in one of your body’s larger veins is called a deep vein thrombosis (DVT). A stationary blood clot, or one that stays in place, may not hurt you. A blood clot that dislodges and begins moving through the bloodstream can be harmful.

One of the most pressing blood clot concerns is when a DVT makes its way to your lungs and gets stuck. This condition, called pulmonary embolism (PE), can stop blood from flowing and the results can be very serious, even fatal. In fact, as many as 100,000 people in the United States die from DVTs and PEs every year.

Arterial clots in the brain are called strokes. Clots can form in the heart arteries, causing heart attacks. Blood clots can also form in the abdominal blood vessels, causing pain and/or nausea and vomiting.

You don’t need to be worried about blood clots that you might see during your period causing these kinds of symptoms or effects.

Who is most at risk for blood clots?

Some risk factors put certain people at higher risk for developing a blood clot.

Blood clots become more common as people get older, especially when they are over age 65. Long hospital stays, surgeries and trauma may significantly increase your risk of blood clots.

Other factors can increase your risk to a lesser degree. You might be more at risk if you:

Some factors are based on lifestyle choices. Risks might be higher if you:

  • Have overweight/obesity.
  • Live a sedentary (or inactive) lifestyle.
  • Smoke cigarettes.

Symptoms and Causes

What are the most common symptoms of a blood clot?

Blood clot symptoms will depend on where a clot forms in your body. Some people may experience no symptoms at all. Blood clots can occur in the:

  • Abdomen: Blood clots in the belly area can cause pain or nausea and vomiting.
  • Arms or legs: A blood clot in the leg or arm may feel painful or tender to the touch. Swelling, redness and warmth are other common signs of blood clots.
  • Brain: Blood clots in the brain (strokes) can cause a range of symptoms, depending which part of the brain they affect. These clots may cause problems speaking or seeing, inability to move or feel one side of your body and sometimes seizure.
  • Heart or lungs: A blood clot in the heart will cause symptoms of a heart attack such as crushing chest pain, sweating, pain that travels down the left arm, and/or shortness of breath. A blood clot in the lungs can cause chest pain, difficulty breathing, and sometimes can lead to coughing up blood.

Diagnosis and Tests

How are blood clots diagnosed?

Blood clot symptoms can mimic other health conditions. Doctors use a variety of tests to detect blood clots and/or rule out other causes. If your doctor suspects a blood clot, he or she may recommend:

  • Blood tests can, in some cases, be used to rule out a blood clot.
  • Ultrasound provides a clear view of your veins and blood flow.
  • CT scan of the head, abdomen, or chest, may be used to confirm that you have a blood clot. This imaging test can help rule out other potential causes of your symptoms.
  • Magnetic resonance angiography (MRA) is an imaging test similar to a magnetic resonance imaging (MRI) test. An MRA looks specifically at blood vessels.
  • V/Q scans test circulation of air and blood in the lungs.

Management and Treatment

How are blood clots treated?

The goal in treating blood clots, especially DVTs, is to prevent the blood clot from getting larger or breaking loose. Treatment can reduce your chances of developing more blood clots in the future.

Treatment depends on where the blood clot is and how likely it is to harm you. Your doctor might recommend:

  • Medication: Anticoagulants, also called blood thinners, help prevent blood clots from forming. For life-threatening blood clots, drugs called thrombolytics can dissolve clots that are already formed.
  • Compression stockings: These tight-fitting stockings provide pressure to help reduce leg swelling or prevent blood clots from forming.
  • Surgery: In a catheter-directed thrombolysis procedure, specialists direct a catheter (a long tube) to the blood clot. The catheter delivers medication directly to the clot to help it dissolve. In thrombectomy surgery, doctors use special instruments to carefully remove a blood clot.
  • Stents: Doctors may decide if a stent is necessary to keep a blood vessel open.
  • Vena cava filters: In some cases, a person might be unable to take blood thinners, and a filter is put into the inferior vena cava (the body’s largest vein) to catch blood clots before they can travel to the lungs.
Care at Cleveland Clinic


How can you prevent blood clots?

You can reduce your risk of blood clots by:

  • Enjoying regular physical activity.
  • Not smoking.
  • Eating a healthy diet and making sure that you stay hydrated.
  • Maintaining a healthy weight.
  • Managing medical problems such as high blood pressure and diabetes.
  • Making sure you’re up to date with cancer screening.

Living With

When should you call the doctor about a blood clot?

If you think you have a blood clot, you go to the nearest emergency room or call 911. Call 911 right away if you have chest pain, trouble breathing or problems seeing or speaking that come on suddenly.

What should you know about living with a higher risk of blood clots or if you have already had a blood clot?

If you are concerned about your blood clot risk in certain situations, such as when you are traveling or after a surgery, your doctor can give you more information on other habits that can help.

If you are able to walk around while you are traveling, you should make sure you do so at least once every couple of hours. If you are traveling by air, your provider might suggest you wear compression stockings. You can do exercises that move your feet and legs while you are sitting.

If you have a blood clot, your provider might suggest that you take anticoagulants for a certain period of time. Some people may need to take them for life. Make sure you understand how you should take this medication and what types of interactions you should avoid. It is important to have regular follow with a provider who is specifically discussing blood thinner medication with you.

A note from Cleveland Clinic

A blood clot can be serious, even fatal. If you know you are at risk for blood clots, you can help yourself by moving around, by eating well and maintaining a healthy weight and following your healthcare provider’s suggestions on medication and lifestyle changes. (For instance, if you smoke, stop.)

Last reviewed by a Cleveland Clinic medical professional on 09/24/2020.


  • American Society of Hematology. Blood Clots. ( Accessed 9/29/2020.
  • Centers for Disease Control and Prevention. Impact of Blood Clots on the United States. ( Accessed 9/29/2020.
  • National Blood Clot Alliance. About Clots. ( Accessed 9/29/2020.
  • National Heart, Lung, and Blood Institute. Venous Thromboembolism. ( Accessed 9/29/2020.
  • North American Thrombosis Forum. Life After a Blood Clot. ( Accessed 9/29/2020.
  • Radiological Society of North America. Blood Clots. ( Accessed 9/29/2020.
  • World Thrombosis Day. Understanding Thrombosis: Open Your Eyes to Venous Thromboembolism (VTE). ( Accessed 9/29/2020.

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