Blood clotting is a normal and important process in the body. It often occurs to repair injured blood vessels. According to the American Society of Hematology, the human body naturally dissolves blood clots after the internal injury has healed.

However, when clots don’t dissolve naturally, they may restrict normal blood flow to the heart, turning into a serious medical condition.

Common types of blood clots

The two major types of dangerous blood clots are called deep vein thrombosis (DVT) and pulmonary embolism. Though they share many similarities, they occur differently: A DVT develops in a blood vessel and reduces blood flow through the vessel, while embolism occurs when a piece of a blood clot becomes stuck in a blood vessel, obstructing the flow of blood.

Moreover, one can (and usually does) lead to another. In many cases, an embolism develops when a DVT in the leg veins travels to the lung and lodges itself there. This can happen suddenly or slowly over time.

The Centers for Disease Control and Prevention (CDC) states that as many as 100,000 Americans die each year from deep vein thrombosis (DVT) or pulmonary embolism, which is why it’s so important to know the warning signs.

Though symptoms can be sneaky, many people are able to identify them and seek medical attention to treat the clot.

Subtle signs you’re dealing with a dangerous clot

“Developing a DVT is considered a tip-off that a pulmonary embolism could follow,”  Alan Ackermann, DO, founder and medical director of Aventura Institute for Cardiovascular Wellness in Aventura, Florida told Everyday Health.

DVT signs to look for include:

  • Swelling
  • Pain
  • Redness
  • Warmth to the touch
  • Worsening leg pain when bending the foot
  • Leg cramps
  • Discoloration of skin

The most common signs and symptoms of pulmonary embolism, according to the National Heart, Lung, and Blood Institute are:

  • Shortness of breath
  • Chest pain
  • Unexplained cough
  • Rapid heart rate

Symptoms of smaller pulmonary embolisms may not be as obvious. These may include:

  • Lightheadedness
  • Anxiety or dread
  • Passing out 
  • Rapid breathing
  • An irregular or rapid heartbeat 
  • Sweating 

Catching a clot early

There is, however, no need to live in fear of blood clotting. Keep in mind that, according to the American Society of Hematology, blood clots are among the most preventable types of blood conditions.

Staying active, taking all medicines your doctor prescribes, and maintaining a balanced diet are some of the most effective ways to prevent dangerous clotting.