Blood clots form when platelets (blood components) and plasma proteins thicken, forming a semisolid mass. This process may be triggered by an injury or it can sometimes occur inside blood vessels that don't have an obvious injury.
Once these clots form, they can travel to other parts of your body, causing harm. Factors and conditions that can cause troublesome blood clots, as well as serious conditions that are associated with blood clots, include:
- Antiphospholipid syndrome
- Arteriosclerosis / atherosclerosis
- Certain medications, such as oral contraceptives and hormone therapy drugs
- Deep vein thrombosis (DVT)
- Factor V Leiden
- Family history of blood clots
- Heart arrhythmias (heart rhythm problems)
- Heart attack
- Heart failure
- Peripheral artery disease
- Polycythemia vera
- Prolonged sitting or bed rest
- Pulmonary embolism (blood clot in an artery in the lung)
Jan. 11, 2018
Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.
- Blood clots. American Society of Hematology. http://www.hematology.org/Patients/Blood-Disorders/Blood-Clots/5233.aspx. Accessed April 18, 2016.
- Your guide to preventing and treating blood clots. Agency for Healthcare Research and Quality. http://www.ahrq.gov/patients-consumers/prevention/disease/bloodclots.html. Accessed April 18, 2016.
- Longo DL, et al., eds. Bleeding and thrombosis. In: Harrison's Principles of Internal Medicine. 19th ed. New York, N.Y.: McGraw-Hill Education; 2015. http://accessmedicine.com. Accessed April 18, 2016.
- Understand your risk for excessive blood clotting. American Heart Association. http://www.heart.org/HEARTORG/Conditions/More/Understand-Your-Risk-for-Excessive-Blood-Clotting_UCM_448771_Article.jsp. Accessed April 18, 2016.
- What causes excessive blood clotting? National Heart, Lung, and Blood Institute. http://www.nhlbi.nih.gov/health/health-topics/topics/ebc/causes. Accessed April 18, 2016.
- Barbara Woodward Lips Patient Education Center. Preventing blood clots in the veins and lungs. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2012.
- Longo DL, et al., eds. Arterial and venous thrombosis. In: Harrison's Principles of Internal Medicine. 19th ed. New York, N.Y.: McGraw-Hill Education; 2015. http://accessmedicine.com. Accessed April 18, 2016.
- Papadakis MA, et al., eds. Blood vessel & lymphatic disorders. In: Current Medical Diagnosis & Treatment 2016. 56th ed. New York, N.Y.: The McGraw-Hill Companies; 2016. http://accessmedicine.com. Accessed April 18, 2016.
- Lip G, et al. Overview of the treatment of lower extremity deep vein thrombosis (DVT). http://www.uptodate.com/home. Accessed April 18, 2016.