Blood Clot: Symptoms, Causes, Treatment & Prevention

Blood clotting, or coagulation, is a process where your platelets and the proteins in your plasma (the liquid part of your blood) work together to form a mass of blood called a blood clot. This can help you prevent excessive bleeding after an injury. Most of the time, your body will naturally dissolve the blood clot as your injury heals.

However, blood clots can also form on the inside of your blood vessels when there’s no injury. These types of clots do not dissolve on their own, and they can be dangerous.

This condition, known as venous thromboembolism (VTE), is a serious health condition that can have life-threatening consequences. An estimated 900,000 people in the United States are affected by VTE each year, causing about 100,000 deaths. Knowing the signs and symptoms of blood clots and how to prevent them, as well as seeking treatment early, can help you avoid possible complications.

What Is a Blood Clot?

A blood clot is a mass of blood that forms when the platelets and proteins in your blood stick together. Platelets are cell fragments that typically help your blood to clot. Blood clots help the healing process by stopping the bleeding from an injury. They break down and dissolve as your body heals.

In the case of VTE, blood clots form in veins. These types of blood clots can cause health issues and can even be life-threatening.

Here are some examples of VTEs:

• Deep vein thrombosis (DVT): A blood clot deep in a vein in your lower leg, thigh, or pelvis. It can block a vein or cause damage to your leg.
• Pulmonary embolism (PE): A blood clot in your lungs that can prevent your other organs from getting enough oxygen. PE sometimes occurs when a DVT breaks off and travels to your lungs. It can cause symptoms like chest pain, difficulty breathing, coughing, coughing up blood, and irregular heartbeats.
• Cerebral venous sinus thrombosis (CVST): A rare blood clot that occurs in the venous sinuses in your brain. CVST can cause a blockage and lead to a hemorrhagic stroke (a stroke caused by bleeding in or around the brain).

Blood Clot Symptoms

On average, one person in the U.S. dies of a blood clot every six minutes. It’s extremely important to recognize the symptoms of a blood clot so you can get medical treatment right away if necessary.

The location of the blood clot—such as in your arms, legs, lungs, brain, heart, or kidneys—will determine symptoms and possible complications.

Symptoms of DVT Blood Clots

DVT can be difficult to diagnose because you might not experience any symptoms.

Symptoms include:

• Arm or leg swelling
• Leg or arm pain or tenderness not caused by an injury
• Skin redness that is tender to the touch
• Skin that is warm to the touch and swollen or painful

Symptoms of PE Blood Clots

Symptoms of pulmonary embolism vary depending on the clot size, how much of your lung is affected, and any underlying conditions.

Common symptoms include:

• Sudden difficulty breathing
• Chest pain that gets worse when you breathe deeply
• Coughing or coughing up blood
• Leg or back pain
• Extremely low blood pressure, fainting, or feeling lightheaded
• Sweating

Symptoms of CVST Blood Clots

CVST is rare, but recovery depends on early treatment. Get help right away if you experience any of these symptoms:

Get help right away if you experience any of these symptoms:

• Severe headache and nausea
• Seizure
• Difficulty talking or comprehending
• Impaired control of one or both sides of your body
• Vision problems

Causes and Risk Factors

Injuries, surgery, medications, and medical conditions are common causes of blood clots. Understanding these causes can help you work with your healthcare provider to minimize your risk as much as possible.

Injury

When you get hurt or are injured, your body forms a blood clot to stop the bleeding. This type of clotting is normal and usually not something to be concerned about. In fact, as your body heals, the blood clot will dissipate and dissolve.

A head injury may induce bleeding and lead to blood clots in your brain. You might need to have surgery to remove these blood clots as well as to relieve any pressure in your brain.

Surgery or Immobility

About 50% of blood clots occur during a hospital stay or soon after surgery. They can develop in damaged veins and they’re more likely to occur after inflammation or infection, all of which are associated with injuries and surgeries.

Blood clots also are more likely to occur when you are immobile for an extended period of time, such as when you travel long distances or are on extended bed rest.

Medications

Hormone-based medications that contain estrogen can increase your risk of blood clots. These types of medications are typically prescribed to prevent pregnancy, regulate menstrual cycles, or replace hormones during menopause.

Other medications that can contribute to blood clotting include:

• Nolvadex and Soltamox (tamoxifen): A medication used to prevent breast cancer by blocking the effects of estrogen on the body
• Contergan and Thalomid (thalidomide): A medication used to treat cancers and skin disorders
• Epogen (erythropoietin): A medication used to treat anemia in chronic kidney failure

High Cholesterol

When your blood cholesterol levels are too high—especially low-density lipoprotein (LDL) cholesterol—excess cholesterol can stick to your artery walls. This is known as atherosclerosis. As time passes, these deposits harden and form plaque. This plaque can rupture and trigger the formation of a blood clot in an artery. If this process occurs in your heart or brain, the blood clot can lead to a heart attack or stroke.

Some researchers believe that venous (vein) blood clots can also be associated with high LDL. Venous clots aren’t caused by plaques, which only form in arteries. The reason for the connection between venous clots and cholesterol is unclear. Chronic inflammation may play a role, as well as risk factors shared by high LDL and blood clots, like being overweight.

Some researchers theorize that chronic inflammation could be responsible for both high LDL cholesterol and blood clots. In fact, studies have shown that LDL cholesterol can activate your platelets, ultimately leading to blood clots.

Clotting Conditions

Sometimes blood clots occur because you have a condition that causes your blood to clot too easily. These conditions cause overactive clotting, which can lead to bleeding when you run out of platelets.  

Conditions that can cause this excessive clotting include:

• Antiphospholipid syndrome (APS): APS is an autoimmune disorder where antibodies called antiphospholipids attack and damage parts of your cells called phospholipids. This damage increases the likelihood that blood clots form.
• Disseminated intravascular coagulation (DIC): DIC is a rare but serious condition that causes abnormal blood clotting. It can occur after an infection or injury.
• Thrombotic thrombocytopenic purpura (TTP): TTP is a rare, life-threatening condition that causes blood clots to form in small blood vessels throughout your body. These clots can limit or block blood flow to your brain, kidneys, and heart and prevent them from working properly.

Risk Factors

A number of factors can increase your risk of developing a blood clot. For instance, cancer, pregnancy, and surgery are three significant risk factors. Certain medical conditions and medications can also increase your risk.

Here are some of the most common risk factors for developing a blood clot:

• Having obesity
• Remaining immobile for extended periods of time
• Smoking
• Oral contraceptives (birth control pills)
• Physical trauma (injury to a vein due to a broken bone or other serious injury)
• Surgery
• Being over the age of 60
• A family history of blood clots
• Chronic inflammatory diseases (CIDs), such as multiple sclerosis and rheumatoid arthritis, which cause your body to overreact or attack itself
• Diabetes, a condition that affects how your body regulates glucose (sugar) levels
• Hypertension (high blood pressure)
• High cholesterol

How to Know If You Have a Blood Clot

If a healthcare provider suspects a blood clot after reviewing your medical history and doing a physical exam, they may order additional testing to confirm the diagnosis.

Here are some of the tests used to diagnose a blood clot:

• Blood tests: One blood test used to diagnose a blood clot is a D-dimer test. This blood test looks for D-dimer in your blood, which is a protein fragment that is made when a blood clot dissolves in your body. This blood test is often used to diagnose a clotting disorder.
• Imaging tests: A venous ultrasound is commonly used to look for blood clots, particularly in leg veins. This test is a popular approach if DVT is suspected.
• X-rays: Sometimes healthcare providers will use venography to look at your veins or angiography to look at your blood vessels. These tests use a special dye to create clearer images of your veins and blood vessels. They allow healthcare providers to see how your blood is flowing and determine if any clots are interrupting this flow.
• Computerized tomography (CT) scans: A CT scan may be used to detect and diagnose a blood clot. For instance, a CT angiography (CTA) scan can be done on the chest, abdomen, pelvis, or head to look at your body’s blood vessels and search for a blood clot.

Treatment for a Blood Clot

After diagnosing a blood clot, your healthcare provider might refer you to a hematologist. A hematologist is a medical doctor who specializes in blood diseases. The treatment for blood clots largely depends on the type of blood clot, its location, and its severity.

Possible treatments for blood clots include:

• Anticoagulants: These blood-thinning medications are used to prevent blood clots from forming, but they do not break up clots you already have. They can be used to prevent the growth of any existing clots.²³
• Thrombolytics: These medications dissolve blood clots. They’re usually reserved for more severe clots.
• Surgery: Surgery might be necessary to remove a blood clot. For example, a thrombectomy is a technique that removes a blood clot from a blood vessel. Another procedure called catheter-directed thrombolysis involves delivering medication via a catheter (a long tube inserted into your body).

Prevention

Knowing your risk factors and recognizing the signs and symptoms of a blood clot are helpful in prevention.

Here are some other tips:

• Try to get up every hour or so in general. Sitting for long periods of time—whether at work, at sporting events, or while watching TV—can put you at a greater risk for blood clots.
• If possible, stand up and move around periodically if you are traveling long distances, are on bed rest, or if you’ve recently had a serious illness or injury.
• Engage in regular physical activity. Aim to exercise at least 150 minutes each week.
• Avoid smoking. Smoking restricts your blood vessels, which increases your risk of blood clots.
• Maintain a healthy weight.

Healthcare providers also take steps to prevent possible blood clots following surgery—for example, DVT after a total hip or knee replacement. You might take anticoagulation medication before the procedure and wear a compression garment after surgery. Compression garments, including socks, stockings, and sleeves fit very tightly and apply pressure in order to improve circulation.

Complications

Blood clots can block blood flow in your veins. Possible complications depend on the location of the blood clot. The most serious conditions that can potentially be attributed to a blood clot include heart attack, stroke, breathing issues, and even death.

Developing a blood clot in your leg or arm during pregnancy increases the risk of a pulmonary embolism. A blood clot during pregnancy also increases the risk of miscarriage, premature labor (labor that begins before 37 weeks), and even maternal death.

A Quick Review

A blood clot is a mass of blood that forms to stop your body from bleeding when you are injured. They’re an important part of the healing process. However, blood clots can also form even when you haven’t been hurt, putting you at risk for a number of potentially serious complications. Many patients with thromboembolism have a condition or a risk factor that puts them at greater risk of blood clots, even if there is no known injury.

Understanding the symptoms of a blood clot and reaching out to a healthcare provider as soon as possible can help you avoid complications. Many blood clots are treatable if diagnosed early. You can also lower your risk by taking preventative steps like moving regularly and managing conditions associated with blood clots.