Blood clots can occur under many different circumstances and in many different locations. Blood clots that form in response to an injury or a cut are beneficial, stopping potentially dangerous bleeding. However, a number of conditions can cause you to develop blood clots in critical locations, such as your lungs and brain, and they require medical attention.

Blood clots may also break away from their original source and cause damage elsewhere in your body. Blood clots that break away from a deep vein thrombosis and travel to your lungs may cause a potentially life-threatening blood clot in the lungs (pulmonary embolism).

Blood clots that arise in one of the chambers of your heart, usually due to an irregular heart rhythm such as atrial fibrillation, may travel to your brain and cause a stroke. Blood clots that arise in the arteries of the heart itself may block the flow of blood through that artery and cause a heart attack.

Blood clots that arise from within the carotid arteries in your neck may travel to the brain and cause a stroke.

Factors and conditions that can cause blood clots, as well as serious conditions that are associated with blood clots once they form and travel to other parts of your body, include:

1. Antiphospholipid syndrome
2. Arteriosclerosis / atherosclerosis
3. Certain medications, such as oral contraceptives, hormone therapy drugs and some breast cancer medications
4. Deep vein thrombosis
5. Factor V Leiden
6. Family history of blood clots
7. Heart arrhythmias
8. Heart attack
9. Heart failure
10. Obesity
11. Peripheral artery disease
12. Polycythemia vera
13. Pregnancy
14. Prolonged sitting or bed rest
15. Pulmonary embolism
16. Smoking
17. Surgery

Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.

Source: mayoclinic.org

• Shortness of breath
• Pressure, fullness or a squeezing pain in the center of your chest lasting more than a few minutes
• Pain extending to your shoulder, arm, back or jaw
• A fast heartbeat
• Sudden weakness or numbness of your face, arm or leg
• Sudden difficulty speaking or understanding speech (aphasia)
• Sudden blurred, double or decreased vision

Consult your doctor if you develop these signs or symptoms in an area on an arm or leg:

• Swelling
• Redness
• Numbness
• Pain

Self-care measures
To reduce your risk of developing blood clots, try these tips:

• Avoid sitting for long periods. If you travel by airplane, walk the aisle periodically. For car trips, stop and walk around frequently.
• Move. After you've had surgery or been on bed rest, the sooner you move, the better.
• Change your lifestyle. Lose weight, lower high blood pressure, stop smoking and exercise regularly.

Source: mayoclinic.org