Blood clots are gel-like clumps of blood. They are beneficial when they form in response to an injury or a cut, plugging the injured blood vessel, which stops bleeding.

Some blood clots form inside your veins without a good reason and don't dissolve naturally. These may require medical attention, especially if they are in your legs or are in more critical locations, such as your lungs and brain. A number of conditions can cause this type of blood clot.

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.

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.

Feb. 25, 2021