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6 Signs of a Blood Clot You Shouldn't Ignore

Age, obesity, heart disease and more increase your risk of a dangerous clot. Learn how to spot the signs

spinner image Close up of a woman in a gray robe holding her leg due to pain from a blood clot
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You’ve heard that advice to get up and walk around on the airplane? It’s probably time to start heeding it. Your risk of deep vein thrombosis (DVT) — a dangerous condition in which blood clots form when they’re not needed — increases exponentially with age, says cardiologist Geoffrey Barnes, M.D., a vascular medicine specialist at the University of Michigan Health’s Frankel Cardiovascular Center.

Such DVT clots, which often develop in the lower leg, can keep your blood from getting to vital organs like your heart and brain. Clots also can break off and travel through your bloodstream to your lungs, creating a blockage called a pulmonary embolism that can cause serious damage or death.

As many as 100,000 people die from blood clots each year in the United States, according to the U.S. Centers for Disease Control and Prevention (CDC).

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You’re also at higher risk if you’re obese; if you have lung disease, heart disease, inflammatory bowel disease or recent or recurrent cancer; or if you are on an estrogen-based medication such as birth control pills or hormone replacement therapy.

Scientists have also found a link between COVID-19 and abnormal blood clots, possibly triggered by the high levels of inflammation caused by the disease. That association may loom long after the infection clears. A study published in the journal Circulation found that adults who had COVID-19 had a higher risk for blood clots up to a year later, prompting researchers to encourage people with cardiovascular conditions to stay on top of managing those conditions while the virus continues to spread.

How inactivity boosts risk

Blood clots are useful, of course, to stop bleeding after something like an injury. While they can happen otherwise at any time, they are a particular concern when you’re sedentary or immobile for an extended period.

“We rely on the muscles of the leg to help push blood from the leg back to the heart to start that loop again,” Barnes says. When you’re not walking, “your legs aren’t pumping blood as effectively.”

Experts say you should be especially alert for clot symptoms at these times:

  • After having surgery, particularly if it involved your abdomen, pelvis, hip or legs. About one-half of blood clots occur during or soon after a hospital stay or surgery, according to the CDC.
  • If you have experienced recent trauma (such as a fall or car crash) or a broken bone
  • When you are bedridden for any reason
  • During or shortly after a prolonged car or plane ride

Why you can’t just wait and see

Older patients who develop DVT often attribute their symptoms to other ailments, leading to dangerous delays in diagnosis, says Lee Kirksey, M.D., a vascular surgeon at the Cleveland Clinic. “As we age, we have more aches and pains,” Kirksey says. “You figure if you wait it out, it will go away.”


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But while some small blood clots go away on their own, larger ones rarely do, Barnes says. He and other experts say you should seek medical care if you have any of these common signs and symptoms of a blood clot:

1. Pain or tenderness in one leg

Pain often manifests in the calf or thigh, but it can also extend along your entire leg. “A blood clot is almost always in one leg, not both,” Barnes notes.

2. Leg swelling and redness

Swelling is a common symptom of a clot, and it typically affects your whole leg or your leg from the knee down. “We’re talking significant swelling, not just ankle swelling” from water retention, Barnes says. You may also notice redness, or that your leg feels warm to the touch.

3. A muscle spasm or cramp you can’t shake

Patients use different terms to describe what ends up being DVT, Kirksey says, but some say the pain feels like a charley horse or a leg cramp. Unlike a cramp, however, the pain won’t ebb and flow. “Once the pain begins, it’s generally consistent and does not let up,” Kirksey says.

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4. Pain or swelling in one arm 

Most blood clots form in the leg, but they can also develop in the blood vessels of your arm, particularly if you have a medical catheter or if you recently had surgery in your arm, neck or chest.

5. Chest pain or discomfort

The pain may get worse when you take a deep breath or be accompanied by a feeling that your heart is racing. These are serious symptoms that indicate a clot may have traveled to your lungs or heart. That’s an emergency, Barnes says, so call 911 or go to the hospital immediately.

6. Shortness of breath, dizziness or an unexplained cough

These are also symptoms of a pulmonary embolism blocking oxygen flow. Call 911 or head to the hospital, especially if you also have other symptoms on this list.

What to do if you have symptoms

If you have early symptoms of a clot, such as leg pain or swelling, without shortness of breath or chest pain, start with a call to your primary care provider. He or she will probably order an ultrasound to check for a clot, Kirksey says.

“An important piece of information for patients to understand is that the diagnosis of a blood clot in your leg is made by a very simple test,” Kirksey says. “It’s an ultrasound that’s painless, requires about 15 minutes and can be done in a physician’s office or at a hospital. Yet it can identify a catastrophic DVT and allow us to initiate care so you can avoid significant complications.”

If a clot is found, most patients will be put on a blood-thinning medicine. Special medications to break up the clot may also be used. In rare cases, surgery may be required.

The most important thing to remember, Kirksey and Barnes say, is that if you do have a clot, getting it diagnosed and treated early minimizes your chance of long-term damage and disability.

Editor’s note: This story, originally published Oct. 7, 2021, has been updated to include new information.

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