Causes

By Mayo Clinic Staff

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.

Once these clots form, they can travel to other parts of the body where they can cause harm. There are a variety of factors and conditions that can cause troublesome blood clots, and there are some serious conditions that are associated with blood clots. These include:

  1. Antiphospholipid syndrome
  2. Arteriosclerosis / atherosclerosis
  3. Cancer
  4. Certain medications, such as oral contraceptives and hormone therapy drugs
  5. Coronavirus disease 2019 (COVID-19)
  6. Deep vein thrombosis (DVT)
  7. Factor V Leiden
  8. Family history of blood clots
  9. Heart arrhythmia
  10. Heart attack
  11. Heart failure — a condition in which the heart doesn't pump blood as well as it should.
  12. Obesity
  13. Peripheral artery disease (PAD)
  14. Polycythemia vera — a type of blood cancer.
  15. Pregnancy
  16. Prolonged sitting or bed rest
  17. Pulmonary embolism
  18. Smoking.
  19. Stroke
  20. Surgery

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

From Mayo Clinic to your inbox

Sign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.

We use the data you provide to deliver you the content you requested. To provide you with the most relevant and helpful information, we may combine your email and website data with other information we have about you. If you are a Mayo Clinic patient, we will only use your protected health information as outlined in our Notice of Privacy Practices. You may opt out of email communications at any time by clicking on the unsubscribe link in the email.

March 20, 2025

See also

  1. Dr. Wallace Video
  2. Dr. Mark Truty (surgery, MN) better outcomes with chemo
  3. Buerger disease
  4. Essential thrombocythemia
  5. Mitral valve stenosis
  6. Pancreatic cancer
  7. Pancreatic Cancer
  8. What is pancreatic cancer? A Mayo Clinic expert explains
  9. Infographic: Pancreatic Cancer: Minimally Invasive Surgery
  10. Pancreatic Cancer Survivor
  11. Infographic: Pancreatic Cancers-Whipple
  12. Varicose veins
  13. Endovenous thermal ablation