Excessive Blood Clotting - What Are the Signs and Symptoms of Excessive Blood Clotting? - Signs, Symptoms, and Complications

Signs and symptoms of excessive blood clotting depend on where the clots form. For example, symptoms of a blood clot in the heart or lungs may include chest pain, shortness of breath, and upper body discomfort in the arms, back, neck, or jaw. These symptoms may suggest a heart attack or pulmonary embolism (PE).

Signs and symptoms of a blood clot in the deep veins of the leg may include pain, redness, warmth, and swelling in the lower leg. These signs and symptoms may suggest deep vein thrombosis (DVT).

Signs and symptoms of a blood clot in the brain may include headaches, speech changes, paralysis (an inability to move), dizziness, and trouble speaking or understanding speech. These signs and symptoms may suggest a stroke.

If you have signs or symptoms of a heart attack, PE, or stroke, call 9–1–1 right away. If you have signs or symptoms of DVT, call your doctor right away. The cause of the blood clot needs to be found and treated as soon as possible.

Complications of Blood Clots

Blood clots can form in, or travel to, the arteries or veins in the brain, heart, kidneys, lungs, and limbs. Blood clots can limit or block blood flow. This can damage the body's organs and cause many problems. Sometimes blood clots can be fatal.


A stroke can occur if blood flow to your brain is cut off. If blood flow is cut off for more than a few minutes, the cells in your brain start to die. This impairs the parts of the body that the brain cells control.

A stroke can cause lasting brain damage, long-term disability, paralysis (an inability to move), or death.

For more information, go to the Health Topics Stroke article and the National Institute of Neurological Disorders and Stroke's Stroke Information Pageexternal link icon.

Heart Attack

A blood clot in a coronary artery can lead to a heart attack. A heart attack occurs if blood flow to a section of heart muscle becomes blocked. If blood flow isn't restored quickly, the section of heart muscle becomes damaged from lack of oxygen and begins to die.

This heart damage may not be obvious, or it may cause severe or long-lasting problems such as heart failure or arrhythmias (irregular heartbeats).

For more information, go to the Health Topics Heart Attack article.

Kidney Problems and Kidney Failure

A blood clot in the kidneys can lead to kidney problems or kidney failureexternal link icon. Kidney failure occurs if the kidneys can no longer remove fluids and waste from your body. This causes a buildup of these fluids and waste in your body, high blood pressure, and other health problems.

Pulmonary Embolism

If a blood clot travels from a deep vein in the body to the lungs, it's called a pulmonary embolism, or PE. PE is a serious condition that can damage your lungs and other organs and cause low oxygen levels in your blood.

For more information, go to the Health Topics Pulmonary Embolism article.

Deep Vein Thrombosis

A blood clot in a vein deep in your arm or leg can cause pain, swelling, redness, or increased warmth in the affected limb. This type of clot is called deep vein thrombosis, or DVT. Deep vein clots can break off, travel to the lungs, and cause PE.

For more information, go to the Health Topics Deep Vein Thrombosis article.

Pregnancy-Related Problems

Blood clots can cause miscarriages, stillbirths, and other pregnancy-related problems, such as preeclampsia(pre-e-KLAMP-se-ah). Preeclampsia is high blood pressure that occurs during pregnancy.