A person’s blood clot risk factors can include some acquired or genetic conditions. Although blood clotting plays an important role in protecting a person’s body, abnormal blood clots can be fatal.

Blood clots are masses or clumps of blood that a person’s body forms due to blood vessel damage. Clotting is an important process that keeps a person’s body from harm through excessive bleeding.

A person’s body typically dissolves blood clots after their injury has healed. However, blood clots may not break down, or they may form inside uninjured blood vessels. A person’s body can also sometimes make abnormal blood clots or make too many.

Two commonTrusted Source abnormal blood clot types are deep vein thrombosis and pulmonary embolism (PE). Blood clots can cause people to have serious or possibly fatal medical conditions. These can include strokes or heart attacks.

The Centers for Disease Control and Prevention (CDC) estimate that one American dies from a blood clot every 6 minutesTrusted Source. Another name for excessive blood clotting is hypercoagulability. Some factors can make a person more at risk of blood clots.

Read on to learn more about acquired and genetic blood clot risk factors and health conditions that raise a person’s risk.

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Certain activities, lifestyle factors, or circumstances can raiseTrusted Source a person’s acquired risk factors. Major acquired risk factors for blood clots includeTrusted Source:

  • hospitalization
  • surgery
  • pregnancy

Other acquired risk factors include:

  • smoking
  • obesity
  • prolonged bed rest due to surgery, hospitalization, or illness
  • long periods of sitting, such as during air or car travel
  • physical trauma, particularly if a person has an injury to a vein
  • dehydration
  • organ transplants

Genetic sources of excessive blood clotting are less commonTrusted Source than acquired risk factors. People normally have these risk factors due to variations in their genes. They inherit these alterations from their parents.

People with a genetic blood clotting disorder have an increased risk of blood clots. However, having a genetic disorder does not guarantee that a person will experience a blood clot.

Genetic variations affect the proteins a person’s blood requires to clot effectively. They can also affect the substances that allow a person’s body to dissolve blood clots or delay their formation. People are more likely to have genetic blood clot risk factors if they have:

  • family members who have had blood clots
  • a history of repeated blood clots before 40 years old
  • a history of unexplained miscarriages

Some commonTrusted Source inherited blood clot risk factors include the factor V Leiden alteration, which occurs in 5% of people of European descent, and the prothrombin G20210A variation, which is present in 2% of the population.

Other rarer blood clotting disorders include:

  • deficiencies in blood clotting proteins such as:
    • protein C
    • protein S
    • antithrombin
  • hyperhomocysteinemia — a condition where a person has high levels of homocysteine in their blood
  • sticky platelet syndrome

Some other health conditions can raiseTrusted Source a person’s risk of blood clots. These conditions includeTrusted Source:

  • Cancer: Some types of cancer can raise the amount of proteins in a person’s blood, which can result in blood clots.
  • Atherosclerosis: This is a condition where deposits of fats, cholesterol, and other substances — called plaques — build up in a person’s arteries. If the plaque deposits then rupture, blood clots may form. The clots may block or narrow a person’s artery, causing health problems.
  • Deep vein thrombosis (DVT): DVT is a condition where a blood clot forms in a person’s deep vein. The clots usually develop in a person’s legs but can also develop in their arms. If the clots break off and travel through a person’s blood to their lungs, it can cause serious or fatal complications.
  • Diabetes: People with diabetes have a higher risk of plaque buildup in their arteries. This buildup can cause blood clots to form.
  • COVID-19: People with COVID-19 may developTrusted Source blood clots in multiple places in their bodies. These clots can cause serious complications, including organ damage, heart attack, and stroke. Researchers believe inflammation caused by the SARS-CoV-2 virus may trigger blood clotting.
  • Vasculitis: This disorder causes inflammation and damage in a person’s blood vessels. Clots can then form over the damaged areas.
  • Atrial fibrillation (A-fib): A-fib is the most common type of irregular heartbeat, also known as arrhythmia. Clots form in A-fib when blood fails to pump appropriately from the heart to the rest of the body.

The estrogen in some medications can increaseTrusted Source a person’s risk of developing blood clots. Medications such as contraceptives or hormone replacement therapy (HRT) contain estrogen. The dosage of estrogen, and the way the medication delivers it into a person’s body, affects their blood clot risk.

A person’s risk of blood clots with estrogen-based medication is highestTrusted Source when they first start taking the medication.

People can help reduce their risk of blood clots with certain strategies and lifestyle changes, such as:

  • maintaining a medically recommended weight
  • staying hydrated
  • being physically active, with at least 150 minutes of moderate-intensity activity per week for adults
  • changing sitting or standing position often, especially during long trips
  • eating a diet rich in:
    • fruits
    • vegetables
    • whole grains
  • eating a diet low in:
    • salt
    • red meat
  • managing stress
  • not smoking
  • raising the foot of their bed 4–6 inches
  • occasionally safely raising their legs 6 inches above their heart
  • wearing tight-fitting clothing, including socks or stockings
  • wearing compression stockings if prescribed by a healthcare professional

Blood clotting plays an important role in the body’s bleeding process. However, abnormal blot clots can have serious or possibly fatal complications.

There are many blood clot risk factors. Some medical conditions raise a person’s risk of blood clots. Other blood clots are due to lifestyle factors, medications, and certain genetic conditions. People may be able to reduce their risk of blood clots with simple tips and lifestyle changes.