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You can have no blood clot risk factors and still develop one — which is one reason why it’s important to know the warning signs.

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Blood clots affect everyone differently, but there usually are definite symptoms, says vascular medicine specialist Michael Tran, DO. To help unravel the mystery surrounding blood clots, Dr. Tran shares six of the most common blood clot warning signs.

A blood clot is blood that has partially solidified in a blood vessel. Blood vessels are your body’s highway system. They provide the roads that blood uses to travel from your heart to the rest of your body. There are three kinds of blood vessels:

Blood clots can occur anywhere along the 60,000 miles of blood vessels in your body, but they’re most likely to happen in veins (venous blood clots). The most common kinds of venous blood clots are:

Less common, thankfully, are arterial clots. These occur when a blood clot clogs an artery. “They are a whole different beast,” says Dr. Tran. “The clot can block oxygen from reaching the heart or brain, leading to a heart attack or stroke.”

Early signs of a blood clot can be hard to identify. “Everyone has different symptoms that can range from none to severe,” notes Dr. Tran. “But there are common signs and symptoms of blood clots to be aware of.”

Here are six of them.

DVTs can occur in your legs or arms. The most common signs of a blood clot in your leg include:

Most people typically have some degree of leg swelling, especially near the end of the day. “That’s not the swelling we worry about,” says Dr. Tran. Instead, watch for swelling that:

New leg pain — such as a calf cramp or charley horse — could signal a blood clot in the leg. But if the pain only lasts for a few seconds and doesn’t come back, it’s probably not a blood clot.

“Blood clot symptoms don’t come and go quickly,” says Dr. Tran. “They stay.”

If you have varicose veins, warning signs of a DVT include:

Signs of a blood clot in an arm are similar to the legs but often more noticeable if there’s swelling. Also, arms may turn slightly purple — particularly in your forearm or hand ­— because of the congestion caused by the blood clot, says Dr. Tran.

Symptoms of a pulmonary embolism often depend on:

Some common signs of a blood clot in your lungs include:

Shortness of breath that’s new and different from what you’ve experienced before could be a sign of a blood clot in your lung — especially if the feeling lingers.

“Breathlessness or becoming easily winded with mild exertion will last for hours, even days, if there is a blood clot,” notes Dr. Tran. “If you feel breathless for a second and then you’re OK, it’s probably not.”

While chest pain may signal a heart issue, it can also be a sign of a clot. The chest pain will be constant or happen when you take deep breaths.

“It may feel like a shooting pain that starts in your front and travels to the back in the chest area,” says Dr. Tran. “You may also feel chest heaviness or pressure that lasts. If it’s just fleeting, goes away and doesn’t happen again, you’re probably not dealing with a blood clot.”

Another sign of a blood clot in your lung is coughing up blood. The sputum (spit or mucus) would have more than a tinge of blood in it, too: “It would be much more — teaspoons or tablespoons of blood,” notes Dr. Tran.

Your action plan may vary depending on if you suspect a pulmonary embolism vs. a deep vein thrombosis.

Some pulmonary embolisms can be life-threatening, so go to the emergency room for a doctor’s evaluation if you notice any signs of a blood clot in your lung. Your primary care doctor may send you to the ER so you can get a same-day lung scan, says Dr. Tran.

“The ER can rule out a pulmonary embolism with a CT scan or nuclear medicine ventilation profusion study,” says Dr. Tran. “A CT scan shows doctors your arteries. A nuclear medicine ventilation profusion study is a breathing test with a tracer.”

If your symptoms remain for more than a day or two and worsen, reach out to your primary care doctor. “Your doctor can help you decide your next steps,” recommends Dr. Tran.

If you need help outside of your doctor’s regular business hours, go to the emergency room and not urgent care. “Urgent cares often can’t do ultrasounds, which is the test you need,” says Dr. Tran.

The location of the suspected blood clot matters, too. For example, different leg locations are more worrisome than others.

If the blood clot is in your calf, for instance, your doctor may monitor it by ultrasound with scans every few weeks. If it’s a high-risk blood clot, doctors will often prescribe a blood thinner within 24 hours.

“But it’s not like a stroke where you need to get to the ER within three hours,” says Dr. Tran. “It’s OK to take a wait-and-see approach. Most patients come to us after they’ve had symptoms for several days and do just fine.”

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Signs of a blood clot can vary depending on where it’s located in your body. Our vascular medicine specialist discusses what to look out for, and when to seek help.