Deep Vein Thrombosis (DVT) and PE: Symptoms and Treatment

Deep vein thrombosis (DVT) is a blood clot in a deep vein, most often in the leg. If part of the clot breaks off and travels to the lungs, it becomes a pulmonary embolism (PE), which can be deadly. Doctors call both of these venous thromboembolism (VTE). Both are treated with blood thinners, and sudden shortness of breath or chest pain needs a 911 call.

Key points

Surgery, a hospital stay, long periods of sitting, cancer, pregnancy and estrogen-containing medicines all raise the risk of clots.
A DVT often causes swelling, pain or warmth in one leg. A PE causes sudden shortness of breath, chest pain or fainting.
Ultrasound finds most leg clots. A CT scan of the chest finds most lung clots.
Blood thinners stop clots from growing and lower the chance of new ones. Most people take them for at least three months.
Moving your legs, staying active and taking clot-prevention medicine when advised can prevent many clots.

What causes deep vein thrombosis

Blood clots form more easily when blood flows slowly, when a vein wall is damaged, or when the blood itself clots too easily. Common risks include:

Major surgery, especially hip or knee replacement, and injuries such as a broken leg
Being in the hospital or on bed rest
Sitting for long stretches, such as on flights or drives of more than four hours
Cancer and some cancer treatments
Pregnancy and the first weeks after giving birth
Birth control pills, patches or rings that contain estrogen, and menopause hormone therapy
Being older, carrying extra weight or smoking
A past clot, or a family history of clots
Inherited clotting conditions, such as factor V Leiden
Serious infections, including COVID-19, and long-term illnesses such as heart failure or inflammatory bowel disease

Sometimes a clot forms with no clear trigger.

Symptoms

Deep vein thrombosis

Swelling in one leg, ankle or foot, or less often in one arm
Pain, cramping or tenderness, often in the calf
Warm skin that may look red or darker than usual
Larger veins near the skin’s surface

As many as half of people with a DVT have no symptoms.

Pulmonary embolism

Sudden shortness of breath
Sharp chest pain that gets worse with a deep breath or cough
A fast heartbeat
Coughing up blood
Feeling lightheaded or fainting

How doctors check for blood clots

Risk check. Your doctor will ask about symptoms and risks to judge how likely a clot is.
D-dimer blood test. A normal result, when the chance of a clot is low, makes a clot unlikely. A high result isn’t specific and needs more tests.
Ultrasound of the leg shows clots in the veins and how blood is flowing. You may hear it called a venous Doppler or LENIs (lower extremity noninvasive studies).
CT pulmonary angiogram. Dye is injected into a vein and a CT scan shows clots in the lung arteries.
Ventilation-perfusion (V/Q) scan, which compares air and blood flow in the lungs. It is used when CT dye isn’t safe, for example in some people with kidney disease or during pregnancy.

After a clot with no clear cause, your doctor may suggest tests for clotting disorders or make sure your cancer screenings are up to date.

How deep vein thrombosis and PE are treated

Blood thinners

Blood thinners (anticoagulants) stop a clot from growing and keep new clots from forming. Over weeks to months, the body slowly breaks the clot down on its own. Options include:

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Pills such as apixaban (Eliquis), rivaroxaban (Xarelto), edoxaban and dabigatran
Shots of low-molecular-weight heparin, such as enoxaparin. This is the usual choice during pregnancy.
Warfarin, which needs regular blood tests and care with diet and other medicines

Most people take blood thinners for at least three months. If the clot had no clear trigger, or the risk is ongoing, your doctor may advise taking them long term. Many people with a DVT, and some with a small PE, are treated at home.

Other treatments

Clot-busting medicine (thrombolytics) for a large PE that strains the heart or drops blood pressure
Catheter procedures that break up or remove a clot through a thin tube in a vein
A filter placed in the large vein in the belly to catch clots, for people who can’t take blood thinners. Most filters should be removed once they are no longer needed.
Compression stockings may ease leg swelling and aching after a DVT.

Living with it

Blood thinners raise the risk of bleeding. Tell every doctor and dentist that you take one, and ask before using aspirin, ibuprofen, naproxen or supplements. Get emergency care for black or bloody stool, vomiting blood, a severe headache, or a fall that hits your head.

Some people have long-lasting leg swelling, aching or skin changes after a DVT (post-thrombotic syndrome). A few people stay short of breath months after a PE. Tell your doctor if this happens, because there are tests and treatments for it.

Lowering your risk

After surgery or during a hospital stay, ask about clot prevention. This may include blood-thinner shots or pills, leg pumps, and getting up and walking soon.
On long trips, stand and walk every hour or two. When seated, flex your ankles and squeeze your calf muscles often. Drink water.
If you’ve had a clot or have other risks, ask whether compression stockings help on long flights.
Stay active, keep a healthy weight and don’t smoke.
Tell your doctor about any past clot before starting estrogen or having surgery.

When to see a doctor

See a doctor the same day for swelling, pain or warmth in one leg or arm, especially after surgery, travel or a period of being less active.

Call 911 for sudden shortness of breath, chest pain, coughing up blood, a racing heart or fainting.

Common questions about deep vein thrombosis

Does a blood clot in the leg hurt?

Often, but not always. A DVT usually causes a steady ache, cramp or tenderness in the calf or thigh that gets worse when you stand or walk, along with swelling. Up to half of people have no pain at all, so swelling or warmth in one leg is reason enough to get checked.

Can a blood clot cause pain behind the knee?

Yes. A clot in the vein behind the knee can hurt there, usually with lower-leg swelling that doesn’t go away. Pain behind the knee that comes and goes is more often from a fluid-filled lump (Baker’s cyst), arthritis or a strained tendon. A burst Baker’s cyst can look like a DVT, so get it checked.

Is DVT more common in the left leg?

Yes, somewhat. The main vein from the left leg passes under an artery in the pelvis, which can press on it and slow blood flow. When this pressure is strong, it is called May-Thurner syndrome. Clots still form in either leg, so new swelling on either side matters.

How long does a DVT take to go away?

Pain and swelling usually ease over a few weeks once you start a blood thinner. The body breaks the clot down slowly over weeks to months, and some scarring may stay in the vein. Keep taking your medicine for as long as your doctor advises, even after you feel better.