Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Deep Vein Thrombosis Health Center

Font Size

What Causes Deep Vein Thrombosis (DVT)?

Deep vein thrombosis (DVT) is a blood clot that forms in a vein inside a muscle. It usually happens in your legs, but you can also get them in your arms, chest, and other areas of your body.

It can be serious. It may make your leg hurt and swell. The clot might move and get stuck in a blood vessel in your lungs, brain, or heart. That could cause organ damage and even death -- within hours.

Recommended Related to DVT (Deep Vein Thrombosis)

How Weight Affects DVT

Obesity has more than doubled since 1980 worldwide. The number of deep-vein clots is rising right along with that. Doctors aren't yet sure exactly why, but people who have a body mass index of at least 30 are more likely than people of normal weight to get a blood clot deep in a vein, called deep vein thrombosis, or DVT.

Read the How Weight Affects DVT article > >

The main cause of DVT is poor blood flow. When it slows, blood can pool, which gives the cells a chance to stick together and start clotting. Someone whose blood clots easily is also at greater risk.


You're more likely to get a clot after any surgery that reduces blood flow to a part of your body or after major surgery on your legs, belly, or chest. That includes orthopedic surgery, such as a hip replacement, and abdominal surgery where you'll be under general anesthesia for more than 30 minutes.

The procedure could set tissue, protein, and fats loose in your veins. If the wall of a vein gets accidently damaged, it can release chemicals that trigger blood clotting.

Following major surgery, you'll probably be on bed rest. You won't be using your leg muscles, and that slows your blood flow.

Medical Conditions and Treatments

DVT can happen at any age, but being older than 60 makes it more likely.

Any illness that puts you in bed for more than 3 days can set you up for DVT. And if you've had circulation or clotting problems before, you could have them again.

These are some of the most common medical risk factors for DVT:

Today on WebMD

TAG dvt blood clot
Symptoms, causes, risk factors, and more.
businesswoman in airport
Tips to prevent another clot.
blood thinners
Tips for DVT.
Blood clots in artery
Causes and treatments.
Simple Steps to Lower Cholesterol
Having Surgery Tips To Reduce DVT Risk And More
New DVT Therapies On The Horizon
Atrial Fibrillation Guide

WebMD Special Sections