When blood vessels, which carry blood throughout your body, get injured, clots form to stop the bleeding. As you heal, your body should absorb the clots as they dissolve. However, sometimes these clots remain and restrict blood flow.

A clot that forms in a major vein is called deep vein thrombosis (DVT).

Although DVTs are most likely to form in the deep veins of your legs, they can also form in your arms, according to the American Society of Hematology. It's possible for them to develop in your pelvis and other deep veins as well.

Symptoms of a Blood Clot in the Arm

DVT in your arms or elsewhere can be life threatening. “DVT in the arm is less common than in the legs,” says Melissa Baldwin, MD, assistant professor of surgery at the Icahn School of Medicine at Mount Sinai in New York City. But it’s equally disconcerting, says Dr. Baldwin.

As many as 100,000 Americans die each year from DVT, according to the American Society of Hematology.

It’s important to know the signs of a blood clot in your arm and to seek medical attention right away if you experience them, according to the National Blood Clot Alliance.

“DVT in your arm often presents with swelling and pain,” says Baldwin. Your hand as well as much of your arm may look swollen. The swelling is likely isolated to the affected arm and starts where the clot has formed. Swelling is most likely to occur if the blood clot is in a vein that’s close to the surface of your skin, according to Cleveland Clinic.

The pain from a blood clot in your arm feels like cramping, due to the fact that the clot is blocking the vein and reducing the amount of oxygen that can travel through it.

Discoloration is another possible symptom of a blood clot in the arm. The skin on your arm may look red, purplish, or bluish around the area of the clot. “The discoloration is due to venous congestion,” says Baldwin. Venous congestion occurs when the flow of blood into the vein is greater than the flow out of it. The skin around the clot may be warm to the touch as well.

Causes of a Blood Clot in the Arm

According to the National Blood Clot Alliance, risk factors for a blood clot in the arm may include:

• Surgery or an injury to veins and arteries
• Smoking
• Obesity
• Pregnancy or hormone therapy
• Age over 60
• Cancer or cancer treatment
• Family history of blood clots

Young competitive athletes may be particularly susceptible to a blood clot in an armpit, according to Cleveland Clinic.

When you use your arm repeatedly, your collarbone, first rib, or surrounding muscle can compress veins in your armpit or in the front of your shoulder (the subclavian vein). When a vein is compressed, it can become inflamed. Over time, fibrous tissue can build up, making the vein too narrow for a normal amount of blood to flow through it, resulting in a clot.

“Patients with chest or arm implants such as a pacemaker, defibrillator, or catheter also can develop blood clots in their arms,” says Baldwin.

Treatment for a Blood Clot in the Arm

While there are some self-care steps you can take, like keeping your arm elevated above your heart to reduce swelling and pain, a blood clot should always be evaluated by your doctor.

In doing so, your doctor may prescribe a blood thinner to help stop the clot from growing and traveling to another part of your body, such as your lung, where it can do serious damage, according to Cleveland Clinic.

You may need to wear a compression sleeve to increase blood flow from your hand to your heart. Physical therapy and home exercises could also be part of your treatment plan.

If these steps don't resolve the problem, your doctor may suggest delivering clot-busting medication into the clot itself via a catheter or surgically removing it, according to the American Society of Hematology.