Blood Clots: What They Are, Causes, Symptoms & Treatment

Blood Clots: What They Are, Causes, Symptoms & Treatment
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Medically Reviewed By:
Mark Arredondo, M.D.

A blood clot is a lump of blood that can form in various body parts, including the legs, arms, lungs or heart. These clots can lead to severe health issues.

This article will examine what blood clots are, their causes and symptoms. It's important to note that 3 in 10 people who experience a blood clot may face another episode within a decade, according to the U.S. Centers for Disease Control and Prevention (CDC).

What is a blood clot?

A blood clot is a semi-solid mass made up of blood cells and other substances that forms within your blood vessels.

Normally, these clots help stop excessive bleeding when you're injured or have surgery, according to the Cleveland Clinic. But blood clots can also develop due to specific medical conditions, posing life-threatening risks. Here's where blood clots can occur:

  • Veins: Clots can form in the arms and legs

  • Arteries: They may develop in the lungs, causing a pulmonary embolism

  • Brain: Clots obstructing blood flow to the brain can result in a stroke

  • Heart: Clots in the heart can lead to a heart attack

What causes blood clots?

Blood clots can develop for various reasons, according to Penn Medicine. Some common causes include:

  • Injuries: Clots are more likely after an injury

  • Medical conditions: People with cancer, obesity, liver or kidney disease are at higher risk

  • Smoking: Increases the risk of blood clots

Inherited conditions can also make you prone to abnormal blood clots. These include:

  • Factor V Leiden mutation

  • Prothrombin G20210A mutation

  • Rare conditions like protein C, protein S and antithrombin III deficiencies

Blood clots during hospitalization

Hospitalization, especially after physical trauma, surgery or extended immobility, heightens the risk of blood clots, according to the CDC. A clot occurring in a large vein, often in the leg or arm, is termed a deep vein thrombosis.

Nearly half of all blood clots arise during or within three months of a hospital stay or surgical procedure.

Coincidentally, a study published in the American Heart Association journal Circulation reported that within a week after a COVID-19 diagnosis, the likelihood of experiencing an arterial blood clot was nearly 22 times higher than in individuals not affected by COVID-19. Arterial blood clots could result in a heart attack or ischemic stroke.

This risk significantly decreased in the second week, becoming less than four times higher, the study found.

"I do think that that is a new element to the story — that the risk is not only around the time of the acute COVID infection," Dr. Karen Furie, chief of neurology at Rhode Island Hospital and chair of neurology at Brown University's Warren Alpert Medical School in Providence, R.I., said in an article published by the American Heart Association.

Elevated risks persisted no matter whether an individual required hospitalization due to COVID-19, although risks were more pronounced in those who were hospitalized. Additionally, the research revealed that clot risks were higher in both Black people and Asian populations.

Blood clot symptoms

Deep vein thrombosis (DVT) happens when a blood clot forms in one of your deep veins, often in your legs or occasionally in your arm. The National Blood Clot Alliance suggests keeping an eye out for these DVT signs and symptoms:

  • Swelling, typically in one leg (or arm)

  • Leg tenderness or pain, often resembling a cramp or Charley horse

  • Bluish or reddish skin discoloration

  • Warm leg (or arm) to the touch

These blood clot symptoms may resemble a pulled muscle or Charley horse but can differ as they might involve swelling, skin discoloration and warmth. Contact your doctor immediately if you notice these signs, as immediate treatment may be necessary.

Pulmonary embolism

Blood clots can dislodge from a DVT and travel to the lung, leading to a potentially fatal condition known as pulmonary embolism (PE). Be alert to these PE symptoms:

  • Sudden shortness of breath

  • Sharp, stabbing chest pain that worsens with deep breaths

  • Rapid heart rate

  • Unexplained cough, occasionally with bloody mucus

If you experience these PE symptoms, call 911 or seek immediate emergency room treatment via ambulance. Time is crucial when dealing with a possible pulmonary embolism.

What does a blood clot feel like?

An estimated 900,000 people in the U.S. will have blood clots each year, with 1 in 9 facing death, according to the University of Maryland Medical System. Recognizing the signs of a blood clot, particularly if you're at higher risk, is vital.

Sometimes, blood clots remain silent until they trigger a PE. A clot in the leg might mimic a pulled muscle, while one in the lung can feel like someone's weight pressing on your chest, making it hard to breathe.

To help remember these warning signs, use the acronym STOP (the) CLOT:

  • Swelling in the leg or arm

  • Tenderness or cramps in the leg

  • Out of breath, or shortness of breath

  • Passing out or feeling lightheaded

  • Chest pain or back pain when breathing

  • Leg discoloration, appearing red or blue

  • Overdrive, when your heart races

  • Time to call 911

Blood clot treatment

The treatment of blood clots depends on their location and severity. Different options are available:

For veins (deep vein thrombosis — DVT)

Treating blood clots in the veins involves measures to prevent clot growth and safeguard your health, including:

  • Blood-thinning medications: Injection of anticoagulants like low molecular weight heparin, fondaparinux (Arixtra), or apixaban (Eliquis) prevents clot growth in deep veins.

For arteries

Treatment for a blood clot in the arteries requires prompt action to reestablish normal blood flow and prevent complications.

  • Medication: Clot-dissolving medications and anticoagulants can restore blood flow to the heart or brain

  • Surgery: Surgeons may unblock, reroute or graft blood vessels to bypass blockages

For the brain (stroke)

Treating blood clots in the brain (stroke) demands immediate and targeted interventions to minimize damage and improve outcomes.

  • Emergency IV medication: Administered to break up brain clots, preventing spread

  • Anticoagulants: To reduce clot formation and increase recovery chances

  • Surgery: In complex cases, surgery removes clots and restores blood flow

  • Vena cava filters: If you have a blood clot that can't be removed, a doctor could place a filter in your vena cava, a large vein in the middle of your body, to protect against clots in the legs from moving to the lungs

For the heart and lungs

Treating a blood clot in the heart and lungs typically requires a combination of strategies.

  • Thrombolytics: These medications rapidly dissolve clots but raise bleeding risks

  • Surgery: May be considered to remove the heart clot, depending on the situation

Each treatment method addresses the specific needs and challenges associated with blood clots in different parts of the body.

Living with a blood clot

While pulmonary embolisms are a serious concern, most DVT patients learn to deal with the risk of recurrence. Blood thinners, often prescribed, may be temporary or lifelong based on the cause, demanding caution due to potential bleeding risks.

The American Lung Association explains that a hypercoagulability evaluation to assess your increased tendency to clot may follow your diagnosis, searching for genetic or other risk factors. In rare cases where blood thinners aren't viable, an inferior vena cava (IVC) filter can be considered to stop blood clots from going into the lungs. Its benefits and risks require thorough discussion with your physician.


American Heart Association: Blood Clot Risk Remains Elevated Nearly a Year After COVID-19

American Lung Association: Living with DVT/Blood Clots

Cleveland Clinic: Blood Clots

Johns Hopkins Medicine: Inferior Vena Cava (IVC) Filter Placement

Nanavati Max: Blood Clot in Brain: Symptoms, Diagnosis & Treatment

National Blood Clot Alliance: Signs and Symptoms of Blood Clots

NHS Inform: Arterial thrombosis

Penn Medicine: What are Blood Clots?

U.S. Centers for Disease Control and Prevention (CDC): Hospitalization: A Major Risk Factor for Dangerous Blood Clots

U.S. Centers for Disease Control and Prevention (CDC): Impact of Blood Clots on the United States

University of Maryland Medical System: Know the Warning Signs of a Blood Clot

Yale Medicine: Blood Clot in Veins, Heart, and Lungs

What This Means For You

Knowing the signs of a blood clot and what to do can save your life.

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