
Clotting is a life-saving measure your body takes to prevent itself from bleeding out during an injury. Platelets and proteins in the plasma of your blood jump into action within the first second to minutes after your blood vessel is injured (1). (Updated June 14, 2024)
These clots form a barrier that temporarily seals off the site of injury to keep bacteria and matter out. When the blood vessel is healed, the clot naturally dissolves. When clots form inappropriately inside your blood vessels, however, it can be a recipe for disaster.
Up to 900,000 people develop vascular blood clots in the United States every year. If caught in time, blood clots can be safely dissolved. If not, they will gradually decrease blood flow throughout the body or even migrate towards the lungs, heart, or brain, where they can prove fatal. In fact, roughly 1 in 3 people to suffer from blood clots will die of the condition.
What you Need to Know About Blood Clots

The most important factor in increasing survival is to be able to recognize blood clots early on in their formation. Knowing why they occur is incredibly helpful too.
Common causes include:
- Antiphospholipid syndrome
- Arteriosclerosis / atherosclerosis
- Certain medications, such as oral contraceptives, hormone therapy drugs, and some breast cancer medications
- Factor V Leiden
- Family history of blood clots
- Heart arrhythmias
- Hiatal hernia
- Heart failure
- Obesity
- Peripheral artery disease
- Polycythemia vera
- Pregnancy
- Prolonged sitting or bed rest
- Smoking
- Stroke
- Surgery
Blood clots in the arms and legs can cause (2):
- Swelling
- Pain
- Tenderness
- A warm sensation
- A pale or bluish discoloration
These clots can also be a sign of Deep Vein Thrombosis (DVT), which occurs “…when a blood clot (thrombus) forms in one or more of the deep veins in your body, usually in your legs.”
“Deep vein thrombosis can also happen if you don’t move for a long time, such as after surgery, following an accident, or when you are confined to a hospital or nursing home bed,” writes the Mayo Clinic (3). DVP typically presents itself a tender, cramp-like pain, muscle soreness or a charley horse.
Pulmonary Embolism Symptoms
A pulmonary embolism is a blockage of in one of the pulmonary arteries in your lungs, typically caused by a blood clot. This causes a fatal blockage of blood flow to the lungs (4).
Patients suffering from deep vein thrombosis are more likely to suffer from a pulmonary embolism. Common symptoms include shortness of breath, chest pain, cough, and bloody or blood-streaked phlegm.
Other symptoms include:
- Clammy or discolored skin (cyanosis)
- Fever
- Excessive sweating
- Rapid or irregular heartbeat
- Lightheadedness or dizziness
All the symptoms above should be taken seriously and require emergency care.
Blood clots in the brain, which are just as deadly, can manifest themselves as the weakness of the face, arms or legs, difficulty speaking, vision problems, sudden and severe headache, and dizziness.
Prevention and Treatment
Once at the hospital, doctors can diagnose blood clots thanks to an ultrasound or MRI. A blood test may also be in order.
Your doctor may treat the condition with anticoagulants, thrombolytics, and/or surgery.
Preventing blood clots is much easier, and far less risky than treating them. To keep your vascular system healthy, exercise daily, quit smoking, maintain a healthy blood pressure and cholesterol, and visit your doctor regularly to check your blood pressure (5).
Women who are pregnant, on birth control, or taking hormone replacement therapy, as well as anyone with a family history of blood clots should discuss blood clot prevention with their doctor.