Most people who have factor V Leiden never develop signs or symptoms. The first indication that you have the disorder may be the development of a blood clot (thrombosis).

Some clots do no damage and disappear on their own. Others can be life-threatening. Symptoms of a blood clot depend on where it forms and whether and where it travels.

A clot in a deep vein

This is known as deep vein thrombosis (DVT). Deep vein thrombosis may not cause any symptoms. If signs and symptoms do occur, they commonly affect your legs, including swelling of your ankles and feet. Other signs and symptoms may include:

  • Pain
  • Significant swelling
  • Redness
  • Warmth

A clot closer to the surface of your skin

This is referred to as superficial venous thrombosis, phlebitis or thrombophlebitis. Signs and symptoms usually include:

  • Warmth
  • Tenderness or pain, often in or around the vein with the blood clot
  • Redness

A clot that travels to your lungs

Known as a pulmonary embolism, this occurs when a deep vein clot breaks free and travels through the right side of your heart to your lung, where it blocks blood flow. This can be a life-threatening situation. Signs and symptoms may include:

  • Sudden shortness of breath
  • Chest pain when breathing in
  • A cough that produces bloody or blood-streaked sputum
  • Rapid heartbeat (tachycardia)

When to see a doctor

Seek medical attention immediately if you:

  • Have signs or symptoms of a pulmonary embolism, such as chest pain or discomfort.
  • Have signs or symptoms of deep vein thrombosis, such as leg pain and swelling.

See a doctor if you:

  • Have a family history of blood clots or if family members have factor V Leiden. Ask your doctor about the risks and benefits of genetic testing for the disorder.
  • Have had one or more blood-clotting incidents without an apparent cause, especially if you're under 50.
July 14, 2015