Most patients with factor V Leiden never develop symptoms, according to Mayo Clinic. However, blood clots that develop as a result of the disorder range from being harmless and disappearing without treatment to being life-threatening, depending on the location of the clot.
The development of a blood clot is often the first indication that a person has Factor V Leiden, states Mayo Clinic. When the clot occurs close to the surface of the skin, it may cause warmth, redness or swelling in the area of the clot. If the clot develops in a deep vein, a condition called DVT, symptoms may include extreme swelling, pain, redness and warmth. Sometimes a deep vein clot makes it way through the heart and into the lung, where it blocks blood flow. This is known as a pulmonary embolism and is life-threatening, with symptoms such as shortness of breath, chest pain when inhaling, a cough with bloody sputum and rapid heartbeat.
Standard treatment for blood clots involves the use of anticoagulant medications, such as heparin or warfarin, which thin the blood. These medications increase the risk of excessive bleeding and require close monitoring by a physician, advises Mayo Clinic. For patients with factor V Leiden who do not have blood clots, doctors usually do not prescribe anticoagulants except in circumstances that pose a high risk of blood clot formation, such as surgery.