Blood Clots 101
Symptoms
Diagnosis
Management
Prevention
What to Expect
Living Well
Blood clots form when your body’s clotting system—designed to stop bleeding—activates when it’s not needed. Normally, clotting protects you after an injury, but when a clot forms inside a blood vessel when it’s not needed, it can block blood flow and prevent oxygen from reaching tissues.
This process is called thrombosis, and it can affect veins or arteries anywhere in the body. If a clot travels through the bloodstream and becomes stuck elsewhere, it’s called an embolism. Both can be serious if left untreated. Clots that form in the veins often lead to deep vein thrombosis (DVT) or pulmonary embolism (PE). Those that form in the arteries can cause a heart attack, stroke, or organ damage.
With awareness, early diagnosis, and proper management, most blood clots can be prevented or successfully treated.
A blood clot is a mass of blood that has changed from liquid to a gel-like state. Your body makes clots as a normal response to bleeding. When you cut yourself, clotting helps stop the bleeding and allows healing to begin.
Problems arise when clots form inside your blood vessels without an injury. These unwanted clots can partially or completely block blood flow. The medical term for this is thrombosis.
There are two main types of dangerous blood clots:
Deep vein thrombosis (DVT)—clots that form in deep veins, usually in your legs
Pulmonary embolism (PE)—clots that travel to your lungs
Blood clots affect about 900,000 Americans each year. They can happen to anyone, but certain factors increase your risk. While blood clots can be serious, early detection and proper treatment can prevent complications and save lives.
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Symptoms & Causes
Blood clot symptoms depend on where the clot forms in your body. Some people don’t notice symptoms right away, which is why it’s important to recognize early warning signs.
DVT symptoms in your leg may include:
Swelling in one leg
Pain or tenderness, often starting in your calf
Skin that feels warm to the touch
Red or discolored skin
Pulmonary embolism symptoms may include:
Sudden shortness of breath
Chest pain that worsens with deep breathing
Rapid heart rate
Coughing up blood
Feeling lightheaded or fainting
Common risk factors include:
Sitting for long periods (travel, bed rest, surgery)
Pregnancy and the first 6 weeks after delivery
Taking birth control pills or hormone therapy
Cancer and cancer treatments
Family history of blood clots
Being over age 60
Smoking
Obesity
Certain medical conditions also increase your risk, including heart disease, inflammatory bowel disease, and inherited clotting disorders.
Diagnosis
If your clinician suspects you have a blood clot, they’ll ask about your symptoms and medical history. They’ll also perform a physical exam to check for swelling, tenderness, and skin changes.
Common tests for blood clots include:
D-dimer blood test: Measures a protein fragment in your blood. High levels may suggest a clot, though other conditions can also raise D-dimer levels.
Ultrasound: Uses sound waves to create images of blood flow in your veins. It’s the most common test for DVT.
CT scan (CT pulmonary angiogram): Uses contrast dye to detect clots in your lungs.
Ventilation-perfusion (V/Q) scan: A nuclear medicine test that looks at how air and blood move through your lungs.
Your clinician will choose tests based on your symptoms and where they suspect a clot might be. Some tests may be repeated to monitor progress or confirm that treatment is working.
Management and Treatment
Treatment for blood clots focuses on stopping the clot from growing and preventing new ones from forming. Your plan will depend on the size and location of the clot, as well as your overall health.
Anticoagulant medications (blood thinners) are the most common treatment.
These medicines don’t dissolve existing clots, but they help prevent new ones and keep current clots from getting larger.
Common options include:
Warfarin: Requires regular blood tests to monitor dose.
Direct oral anticoagulants (DOACs): Medications such as rivaroxaban or apixaban that do not need routine blood testing.
Heparin: An injectable medication often used at the start of treatment for fast-acting protection.
Other treatments may include:
Thrombolytic therapy: Uses medication to quickly dissolve large clots. This is used only for severe or life-threatening clots because it increases bleeding risk.
Inferior vena cava (IVC) filter: A small device placed in a large vein to catch clots before they reach the lungs. It’s used when anticoagulants aren’t an option.
Compression stockings: Help improve blood flow, reduce swelling, and lower the risk of post-thrombotic syndrome.
Most people take anticoagulant medication for at least three months. Some may need longer treatment depending on their risk factors and the cause of the clot.
Prevention
You can take several steps to lower your risk of developing blood clots.
Stay active
Move regularly throughout the day, especially if you sit for long periods. Try to stand, walk, or stretch every hour or two.
During travel
Get up and walk every two hours on long flights.
Do simple calf exercises while seated.
Drink plenty of water.
Consider wearing compression stockings for flights longer than four hours.
After surgery or illness
Follow your clinician’s mobility plan.
Take prescribed medications as directed.
Do recommended exercises, even while in bed.
Lifestyle habits
Maintain a healthy weight.
Don’t smoke.
Exercise regularly.
Medical management
Discuss your risk for blood clots before any surgery or hospitalization.
Share your family history with your care team.
Keep all follow-up appointments if you take anticoagulant medication.
If you have multiple risk factors, your clinician may recommend preventive anticoagulant medication during high-risk times such as surgery or prolonged bed rest.
What to Expect After a Blood Clot
With the right care and follow-up, most people recover well after a blood clot and return to their usual activities.
Short-term recovery
Most blood clots improve within a few weeks to months with treatment. Regular follow-up visits and taking medication as prescribed are key to recovery.
Long-term health considerations
About 3 in 10 people may develop another clot within 10 years.
Some experience ongoing leg discomfort or swelling, known as post-thrombotic syndrome.
In rare cases, a pulmonary embolism can cause chronic lung problems.
Your recovery depends on:
How quickly the clot is diagnosed and treated
The size and location of the clot
Your overall health
Whether the clot was provoked or unprovoked
When blood clots are treated promptly, survival rates are high, and most people return to normal activities within weeks. Staying consistent with medication and follow-up care helps lower the risk of future clots and supports long-term health.
Living with Blood Clots
Whether you’re being treated for a blood clot or you’ve had one in the past, living well means staying informed and proactive.
Taking blood thinners safely
Follow prescriptions exactly as directed.
Keep all lab appointments if you take warfarin.
Watch for signs of bleeding, such as easy bruising, nosebleeds, or blood in your urine or stool.
Tell all of your clinicians and dentists that you take anticoagulant medication.
Daily life adjustments
Wear medical alert jewelry.
Use a soft toothbrush and handle sharp objects carefully.
Choose low-impact activities like walking, swimming, or yoga.
When to seek medical care
Contact your clinician or go to the emergency department right away if you have:
New or worsening leg pain or swelling
Sudden shortness of breath
Chest discomfort
Uncontrolled bleeding
Severe or persistent headaches
Emotional support
Join a blood clot support group or online community.
Talk with a counselor or mental health professional.
Stay connected with loved ones.
Try relaxation techniques such as meditation, journaling, or gentle stretching.
With proper management, most people with blood clots lead active, healthy lives.
References
American Heart Association. Understand your risk for blood clots. Updated 2023. heart.org
Centers for Disease Control and Prevention. Venous thromboembolism (Blood clots). Updated March 2022. cdc.gov/ncbddd/dvt
Kearon C et al. Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report. Chest. 2016;149(2):315-352.
National Institutes of Health. The basics of blood clots: What you need to know. NIH MedlinePlus Magazine. https://magazine.medlineplus.gov/article/the-basics-of-blood-clots-what-you-need-to-know. Published 2023. Accessed November 3, 2025.
van Hylckama Vlieg MA, Nasserinejad K, Visser C, Bramer WM, Ashrani AA, Bosson JL. The risk of recurrent venous thromboembolism after discontinuation of anticoagulant therapy in patients with cancer-associated thrombosis: a systematic review and meta-analysis. eClinicalMedicine. 2023;64:102194. doi:10.1016/j.eclinm.2023.102194