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Published on: 2/24/2026
Deep vein thrombosis is a blood clot in a deep leg vein that can cause one-sided swelling, pain, warmth, or redness and can lead to a life-threatening pulmonary embolism; it occurs when blood flow slows, blood clots more easily, or a vein is damaged. There are several factors to consider and some conditions can mimic it; see below for risk factors, symptom clues, and how doctors confirm it.
If you suspect it, do not massage the leg and seek prompt care for evaluation with D-dimer and ultrasound, and go to the ER immediately for chest pain, shortness of breath, fainting, or coughing blood, with treatment, prevention, and next-step details outlined below.
If you're worried about deep vein thrombosis (DVT), you're not alone. It's a serious but treatable condition. Knowing what it is, why it happens, and what steps to take can help you act quickly and confidently.
This guide explains:
Deep vein thrombosis (DVT) is a blood clot that forms in a deep vein, usually in the leg. Most often, it develops in the:
Less commonly, DVT can occur in the arms.
The main concern with deep vein thrombosis is not just the clot itself, but what can happen if part of it breaks off and travels to the lungs. This can cause a pulmonary embolism (PE), which can be life-threatening and requires immediate medical attention.
That said, many cases of DVT are successfully treated when caught early.
Not everyone with deep vein thrombosis has symptoms. But when symptoms do appear, they often include:
Symptoms typically affect only one leg, which is an important clue.
Seek urgent medical care if you notice:
These could be signs of a pulmonary embolism.
If you're experiencing any of these symptoms and want to better understand your risk level, try Ubie's free AI-powered Deep Vein Thrombosis (DVT) symptom checker before speaking with a healthcare provider.
Doctors often explain deep vein thrombosis using something called Virchow's Triad. It describes three main factors that increase clot risk:
When blood moves too slowly through the veins, it's more likely to clot.
This can happen during:
Even sitting for long periods without moving your legs can contribute.
Some people have blood that is more prone to clotting due to:
Dehydration can also thicken the blood, slightly increasing risk.
Injury to a vein can trigger clot formation. This may occur due to:
You may be at increased risk if you:
Risk increases when multiple factors combine.
Leg swelling and pain are common, and most cases are not deep vein thrombosis. Other causes include:
Because symptoms overlap, you cannot reliably diagnose DVT at home.
If you suspect deep vein thrombosis, it's important to speak to a doctor promptly. Waiting can increase the risk of complications.
A doctor will typically evaluate:
They may use a clinical scoring tool to estimate the likelihood of DVT.
This test measures a substance released when clots break down.
This is the most common and reliable test for diagnosing deep vein thrombosis.
It is:
In rare cases, additional imaging may be needed.
The good news: deep vein thrombosis is treatable.
These medications:
Common options include:
Treatment usually lasts:
Your doctor will determine the safest plan for you.
Rarely, additional treatment may be needed:
These are typically reserved for high-risk or complicated cases.
Untreated deep vein thrombosis can lead to:
A potentially life-threatening condition where the clot travels to the lungs.
Long-term leg symptoms such as:
Early diagnosis and treatment significantly reduce these risks.
If you think you might have deep vein thrombosis, take these steps:
If you're unsure about your symptoms, you can use Ubie's free online Deep Vein Thrombosis (DVT) symptom checker to get personalized insights in just a few minutes and determine whether you should seek immediate medical attention.
However, no online tool replaces a real medical evaluation.
Call emergency services or go to the nearest emergency room if you have:
These could indicate a pulmonary embolism, which requires urgent care.
You can reduce your risk by:
If you are at high risk, your doctor may prescribe preventive blood thinners.
Deep vein thrombosis is a serious condition—but it is manageable and often fully treatable when identified early.
If you are experiencing one-sided leg swelling, pain, warmth, or redness, don't ignore it. While many cases turn out to be something less serious, DVT is not something to self-diagnose or wait out.
Consider starting with a free online symptom check, and most importantly, speak to a doctor if your symptoms could represent something serious or life-threatening. Acting early can make all the difference.
Your health is too important to guess.
(References)
* Kearon C, et al. Diagnosis and Management of VTE: A Review. JAMA. 2021 Jul 13;326(2):182-192. doi: 10.1001/jama.2021.10023. PMID: 34255018.
* Konstantinides SV, et al. 2019 ESC Guidelines for the diagnosis and management of acute pulmonary embolism developed in collaboration with the European Respiratory Society (ERS). Eur Heart J. 2020 Jan 21;41(4):543-603. doi: 10.1093/eurheartj/ehz405. PMID: 31505067.
* Mousa SA, et al. Pathophysiology of Deep Vein Thrombosis: A Critical Appraisal of Virchow's Triad. Adv Exp Med Biol. 2017;906:1-12. doi: 10.1007/5584_2016_62. PMID: 27957777.
* Stevens SM, et al. Antithrombotic Therapy for VTE Disease: CHEST Guideline and Expert Panel Report. Chest. 2021 May;159(5):1930-1951. doi: 10.1016/j.chest.2021.02.013. PMID: 33676274.
* Cushman M. Epidemiology and risk factors for venous thrombosis. Semin Hematol. 2017 Jan;54(1):1-10. doi: 10.1053/j.seminhematol.2017.01.002. PMID: 28410769.
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