Blood clots are gel-like clumps of blood. When they form in response to a cut or other injury, they stop the bleeding by plugging the injured blood vessel. These blood clots help the body heal.
But some blood clots form inside the veins without a good reason. They don't dissolve naturally. These clots may require medical attention, especially if they are in the legs, lungs or brain. A number of conditions can cause this type of blood clot.
Blood clots are made when substances in the blood thicken and form a semisolid mass. This process may be triggered by an injury. Sometimes it occurs inside blood vessels that don't have an obvious injury.
Seek emergency care if you experience:
- Cough that produces bloody sputum.
- A fast heartbeat.
- Lightheadedness.
- Difficult or painful breathing.
- Chest pain or tightness.
- Pain that spreads to the shoulder, arm, back or jaw.
- Sudden weakness or numbness of the face, arm or leg.
- Sudden difficulty speaking or understanding speech.
Consult your health care provider if you develop these symptoms in an area on an arm or leg:
- Swelling.
- Change in skin color, such as an area on the leg that looks unusually red or purple.
- Warmth.
- Pain.
Self-care measures
To reduce the risk of developing blood clots, try these tips:
- Avoid sitting for long periods. If you travel by airplane, walk the aisle now and then. For long car trips, stop frequently and walk around.
- Move. After you've had surgery or been on bed rest, the sooner you get up and move around, the better.
- Drink plenty of fluids when traveling. Dehydration can increase the risk for blood clots.
- Change your lifestyle. Lose weight, lower high blood pressure, stop smoking and exercise regularly.
Show References
- Blood clots. American Society of Hematology. https://www.hematology.org/education/patients/blood-clots. Accessed April 23, 2023.
- Your guide to preventing and treating blood clots. Agency for Healthcare Research and Quality. https://www.ahrq.gov/patients-consumers/prevention/disease/bloodclots.html. Accessed April 23, 2023.
- Loscalzo J, et al., eds. Bleeding and thrombosis. In: Harrison's Principles of Internal Medicine. 21st ed. McGraw Hill; 2022. https://accessmedicine.mhmedical.com. Accessed April 23, 2023.
- Understand your risk for excessive blood clotting. American Heart Association. https://www.heart.org/en/health-topics/venous-thromboembolism/understand-your-risk-for-excessive-blood-clotting. Accessed April 23, 2023.
- Blood clotting disorders: Causes. National Heart, Lung, and Blood Institute. https://www.nhlbi.nih.gov/health/clotting-disorders/causes. Accessed April 23, 2023.
- What is venous thromboembolism? Centers for Disease Control and Prevention. https://www.cdc.gov/ncbddd/dvt/facts.html. Accessed April 23, 2023.
- Loscalzo J, et al., eds. Arterial and venous thrombosis. In: Harrison's Principles of Internal Medicine. 21st ed. McGraw Hill; 2022. https://accessmedicine.mhmedical.com. Accessed April 23, 2023.
- Caforio ALP. COVID-19: Cardiac manifestations in adults. https://www.uptodate.com/contents/search. Accessed April 23, 2023.
Original article: https://www.mayoclinic.org/symptoms/blood-clots/basics/causes/sym-20050850