Blood clots form when certain parts of your blood 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
- Coronavirus disease 2019 (COVID-19)
- Deep vein thrombosis (DVT)
- Factor V Leiden
- Family history of blood clots
- Heart arrhythmia (heart rhythm problems)
- Heart attack
- Heart failure
- Peripheral artery disease (PAD)
- Polycythemia vera
- Prolonged sitting or bed rest
- Pulmonary embolism — a blood clot in an artery in the lung.
Causes shown here are commonly associated with this symptom. Work with your doctor or other health care professional for an accurate diagnosis.
Feb. 25, 2021
From Mayo Clinic to your inbox
Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health. Click here for an email preview.
ErrorEmail field is required
ErrorInclude a valid email address
To provide you with the most relevant and helpful information, and understand which
information is beneficial, we may combine your email and website usage information with
other information we have about you. If you are a Mayo Clinic patient, this could
include protected health information. If we combine this information with your protected
health information, we will treat all of that information as protected health
information and will only use or disclose that information as set forth in our notice of
privacy practices. You may opt-out of email communications at any time by clicking on
the unsubscribe link in the e-mail.
Thank you for subscribing!
You'll soon start receiving the latest Mayo Clinic health information you requested in your inbox.
Sorry something went wrong with your subscription
Please, try again in a couple of minutes
- 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.
- AskMayoExpert. COVID-19: Myocardial injury (adult). Mayo Clinic; 2020.