Blood Clot Signs & Symptoms

What is a blood clot?

Blood flows through blood vessels (arteries and veins), and is constantly in motion as the heart pumps blood through arteries to the different areas (organs, glands, cells etc.) of the body. Blood is then returned back to the heart by the veins. Blood returns to the heart by the motion of the body. Muscles squeeze blood through the veins back toward the heart. Without motion, blood has a tendency to stagnate by gravity, and stagnant blood then has the tendency to clot.  

Blood clotting is an important mechanism to help the body repair injured blood vessels. Blood consists of

  • red blood cells containing hemoglobin that carry oxygen to cells and remove carbon dioxide (the waste product of metabolism),
  • white blood cells that fight infection,
  • platelets that are part of the clotting process of the body, and
  • blood plasma, which contains fluid, chemicals and proteins that are important for bodily functions.

Blood Clot Continued

Complex mechanisms exist in the bloodstream to form clots where they are needed. If the lining of the blood vessels becomes damaged, platelets are recruited to the injured area to form an initial plug. These activated platelets release chemicals that start the clotting cascade, using a series of clotting factors produced by the body. Ultimately, fibrin is formed, the protein that crosslinks with itself to form a mesh that makes up the final blood clot.

The medical term for a blood clot is a thrombus (plural=thrombi). When a thrombus is formed as part of a normal repair process of the body, there is little consequence. Unfortunately, there are times when a thrombus (blood clot) will form when it is not needed, and this can have potentially significant consequences.

How does a blood clot form?

Blood clots form when there is damage to the lining of a blood vessel, either an artery or a vein. The damage may be obvious, such as a cut or laceration, or may not be visible to the naked eye. Blood also will begin to clot if it stops moving, and becomes stagnant, or in diseases that cause the blood to clot abnormally.

Blood clots in a vein (venous thrombosis) occur when a person becomes immobilized and muscles are not contracting to push blood back to the heart. This stagnant blood begins to form small clots along the walls of the vein. This initial clot can gradually grow to partially or completely occlude or block the vein and prevent blood from returning to the heart.

Who is at risk of developing a blood clot? 

You're more likely to develop blood clots if: 

  • you have high blood pressure 
  • you have high cholesterol 
  • you have diabetes
  • severe accident/trauma/injury 
  • are staying in or recently left hospital – especially if you can't move around much (like after an operation)
  • if you are overweight or obese 
  • if you smoke
  • if you have had a blood clot before
  • if you have a family history of blood clots or heart attack/stroke
  • if you are sitting too long 
  • if you have had major surgery done 
  • broken bones, muscle injury/severe injury to vein 


What are the symptoms of a blood clot? 

Seek emergency care if you experience:

  • Cough that produces bloody sputum
  • A fast heartbeat
  • Lightheadedness
  • Difficult or painful breathing
  • Chest pain or tightness
  • Pain extending to your shoulder, arm, back or jaw
  • Sudden weakness or numbness of your face, arm or leg
  • Sudden difficulty speaking or understanding speech (aphasia)
  • Sudden changes in your vision

Consult your doctor if you develop these signs or symptoms in an area on an arm or leg Swelling, Redness, Pain

blood clot blood clot symptoms blood clot risk factors

Blood Clot Prevention Tips 

To reduce your risk of developing blood clots, try these tips:

Avoid sitting for long periods. If you travel by airplane, walk the aisle periodically. For long car trips, stop and walk around frequently.

Move. After you've had surgery or been on bed rest, the sooner you get up and move around, the better.

Drink plenty of fluids when traveling. Dehydration can contribute to the development of blood clots.

Change your lifestyle. Lose weight, lower high blood pressure, stop smoking and exercise regularly.

blood clot prevention blood clot diet blood clot signs

Arterial Blood Clot

These form in your arteries  the blood vessels that carry blood away from your heart. Arterial clots block blood and oxygen from reaching your vital organs. They can lead to tissue damage. Often, they occur in your legs and feet. Sometimes, they happen in your brain, where they can lead to stroke. Or, they may form in your heart, where they can cause a heart attack. The symptoms of arterial blood clots include the following:

  • Cold arm or leg
  • Fingers or hands that feel cool to the touch
  • Muscle pain or spasm in the affected area
  • Numbness or tingling in your arm or leg
  • Weakness of the affected limb
  • Loss of color in the affected limb

Venous Blood Clot

These form in your veins. They tend to develop slowly. That’s why you might not know you have one until it causes problems. There are three types of blood clots that form in the veins superficial venous thrombosis, deep vein thrombosis (DVT), and pulmonary embolism.  

Deep Vein Thrombrosis

This is also called a “venous thrombosis.” It’s a blood clot that forms in a major vein deep in your body. It usually happens in your lower leg, thigh, or pelvis. But it can also form in other parts of your body, like your arm, brain, intestines, liver, or kidneys. 

Pulmonary Embolism 

Pulmonary embolism . This type of blood clot is a medical emergency. It’s a DVT that breaks off and travels up your leg to your lungs, where it gets stuck. It can be fatal.

Superficial venous thrombosis. This is a blood clot that forms in a vein close to the surface of the skin. They don’t normally break loose and travel through the bloodstream. But they can be painful and may require treatment. 

Venous Clot Signs

If your vein is near your skin’s surface (superficial venous thrombosis), these may include:

  • Painful, swollen, inflamed skin over the affected vein
  • A vein that feels hard or painfully tender to the touch
  • Red skin over the affected vein


When to seek medical advice for Deep Vein Thrombrosis: 

If you have a Deep Vein Thrombrosis, you may notice the following:

  • The affected leg is swollen (sometimes both legs swell).
  • You have a cramping pain or soreness in your leg, usually in the calf. It may be worse when you bend your foot back toward your knee.
  • There's an aching, heavy feeling in the affected leg.
  • The skin in the area of the clot is warm or red.

Deep Vein Thrombrosis is a medical emergency. See your doctor right away if you notice these symptoms.

If left untreated, deep vein thrombrosis can turn into a pulmonary embolism. 

Call 999 immediately if you have pain, swelling, or tenderness in your leg, and if you can’t breathe or you have chest pain.