Blood Clot or Leg Pain?


Calf pain can be annoying, but it’s rarely a cause for serious medical concern. The wrong shoes, a muscle cramp, stress, dehydration, remaining in the same position for an extended period, and minor injuries can all lead to aching calves.

But when calf pain is intense, gets worse over time, or distracts you from everyday duties, it could signal a more serious problem. Every year, as many as 900,000 people experience blood clots in a vein or artery. Most of these blood clots occur in blood vessels in the legs, where decreased circulation is common, and when this occurs in a deep vein in the leg, it is known as deep vein thrombosis (DVT). The blood clot itself is never fatal, but if it breaks free, it can travel to your brain, heart, or lungs, and can trigger a deadly cardiovascular episode.

So how can you tell the difference between a muscle cramp and a blood clot? And how do you know if you’re at risk? Only a doctor can say for sure, but knowing what to look for can help you detect a blood clot before it endangers your health.

Who is at Risk for Blood Clots?

Anyone can experience a blood clot, but they most likely occur when something interferes with circulation to your lower extremities. You’re at the most risk if:

  • You frequently travel without stretching your legs. Extended periods of sitting – particularly on international flights if you don’t regularly stretch your legs – can be especially dangerous.
  • You have diabetes, high blood pressure, peripheral artery disease, or another condition that slows circulation to your legs.
  • You are overweight.
  • You are pregnant. Additional weight can slow circulation, and pregnancy significantly increases blood volume, further exacerbating the risk.
  • You smoke or have a history of cardiovascular problems.
  • You are over the age of 50.
  • You’ve recently had surgery on your legs or are on bed rest.
  • You have suffered a serious injury in your legs, such as a wound requiring stitches or a broken bone.
  • You have May-Thurner Syndrome. In May-Thurner syndrome, the right iliac artery puts pressure on the left iliac vein at the point in the pelvis where they cross over one another, potentially constricting blood flow and increasing risk of blood clotting. People with May-Thurner syndrome are more likely to have a deep vein thrombosis (DVT).
  • Blood clotting disorders: “At times patients are born with a clotting disorder that makes them prone to developing blood clots,” said Steven Elias, MD, a vascular surgeon and Director of the Center for Vein Disease in Englewood, NJ. “The disorder by itself may not lead to problems but if you add other risk factors such as those above, then a blood clot can occur. If there is any family history of blood clots in the veins, then one may speak to their physician about being tested.”

Dr. Elias says in order to avoid blood clots, it’s important for people to try “to minimize the risk factors such as immobility, dehydration when traveling, sedentary lifestyle.“

Common Symptoms of Blood Clots

The most common symptom of a blood clot is leg pain that can’t be explained by something else, such as a bruise or recent injury. The pain will be concentrated in one area, not shooting from one spot to another. If pain lasts for more than a few days or is intense, it’s time to be checked out by a doctor. Sometimes the pain accompanies other symptoms, including:

  • Swelling of the feet or ankles
  • Discoloration of the legs or feet
  • Tingling or numbness in the feet
  • Warmth at the site of the pain

Blood Clot or Calf Pain?

“At times the difference between leg cramps or blood clots is very hard to determine,” said Dr. Elias. “But the history is very important.”

To help determine whether the source of your leg pain is a blood clot or something else, you need to tell your doctor what you’ve been doing over the last few days.

“If a patient has been on a long air flight or car ride and then has pain afterward this would more likely be due to a blood clot,” said Dr. Elias “But if the patient did a lot of exercise for a day or two before and wakes up with sore crampy legs this of course would be more likely muscle cramps.”

If basing a diagnosis solely on history and examination, even an experienced vein specialist would only be right 50% of the time.

“This is why we almost always get an ultrasound if we suspect a blood clot at all,” Dr. Elias said.

Imaging techniques such as an ultrasound, MRI or venogram of your legs can tell you for sure whether the pain is due to a muscle injury or blood clot, so consult your doctor if you are worried you might have a blood clot. It is possible even if you do not have the telltale risk factors.

Some common differences between calf pain and blood clots include:

  • Muscle pain that radiates to other spots, and often occurs in both legs, while blood clot pain occurs in a single location.
  • With a blood clot, the pain gets worse over time, rather than gradually going away.
  • Elevation, rest, ice, and other muscle treatment strategies don’t work for a blood clot.
  • There is swelling below the site of the pain, rather than around it. Swelling beneath the pain can indicate a decreased blood supply due to a clot.

Going to the Emergency Room: Better Safe Than Sorry

If you have some unexplained calf pain without major signs pointing to a blood clot, it’s usually fine to wait until the next day to see your doctor if the pain doesn’t subside. However, you should definitely go to the emergency room if you experience “a sudden onset in lower leg pain mostly calf or sudden swelling without any trauma,” said Dr. Elias. You should also go to the emergency room if you have had recent surgery and have not been walking much, and then experience unilateral leg swelling, according to Dr. Elias.

Additionally, if you have multiple risk factors for a blood clot — particularly recent lengthy travel where you couldn’t stretch your legs, or if you are on bed rest — treat the pain as a medical emergency and go to the emergency room. You might be embarrassed if it turns out to be nothing, but if you have a blood clot, acting fast could save your life.

Most calf pain will go away on its own, so there’s no need to panic with each ache you experience in your calf. But calf pain should be taken seriously if it is intense and does not go away. Blood clots are highly treatable, so a simple consultation with your doctor could save your life.