Thrombosis is the formation of a blood clot inside a blood vessel. The clot can partially or completely block blood flow. Depending on where it occurs, thrombosis can be a medical emergency.
The two main types are:
- Deep vein thrombosis (DVT): A clot in a deep vein, usually in the leg.
- Arterial thrombosis: A clot in an artery, which can lead to a heart attack or stroke if it blocks blood flow to the heart or brain.
Common symptoms
Deep vein thrombosis (DVT):
- Swelling in one leg (or one arm, less commonly)
- Pain or tenderness, often in the calf
- Warmth over the affected area
- Red or discolored skin
Pulmonary embolism (PE) (when part of a DVT travels to the lungs) is a medical emergency. Symptoms may include:
- Sudden shortness of breath
- Chest pain that may worsen with deep breathing
- Rapid heartbeat
- Coughing up blood
- Feeling faint or collapsing
Arterial thrombosis may cause:
- Sudden severe pain
- Cold, pale limb
- Weakness or loss of movement
- Symptoms of a heart attack or stroke, depending on the affected artery
Risk factors
Your risk of thrombosis is higher if you:
- Sit still for long periods (such as during long flights or bed rest)
- Have surgery or a major injury
- Smoke
- Have obesity
- Are pregnant or recently gave birth
- Use estrogen-containing birth control or hormone therapy
- Have cancer or certain inherited clotting disorders
- Are older or have a previous history of blood clots
Ways to help reduce your risk
Some everyday habits can lower the risk of blood clots:
- Stay physically active and avoid prolonged sitting.
- Get up and walk every 1–2 hours during long trips.
- Stay well hydrated.
- Maintain a healthy weight.
- Avoid smoking.
- Manage conditions such as diabetes, high blood pressure, and high cholesterol.
- Take prescribed blood-thinning medication exactly as directed if your healthcare professional has recommended it.
There is no natural remedy that has been proven to prevent thrombosis in people at risk. Herbs, supplements, or foods should not be used as a substitute for prescribed anticoagulant medication or other medical treatment.
When to seek emergency care
Seek immediate medical attention if you have:
- Sudden swelling and pain in one leg, especially if it’s accompanied by warmth or redness.
- Sudden shortness of breath, chest pain, coughing up blood, or fainting.
- Signs of a stroke (sudden weakness on one side, facial drooping, trouble speaking).
- Symptoms of a heart attack (chest pressure, pain spreading to the arm, jaw, or back, along with shortness of breath or sweating).
Prompt diagnosis and treatment can be lifesaving and significantly reduce the risk of serious complications.
