A blood clot can be life-threatening when left untreated, yet the symptoms often go unnoticed or mistaken for less serious issues. These clots, which form when blood thickens and clumps together, can block blood flow to critical areas like the lungs, brain, or heart. Recognizing the subtle signs is crucial, as early detection can prevent serious complications such as pulmonary embolism, stroke, or even death. Many of these signs can seem minor or unrelated, making it easy to overlook them. By understanding the silent signals your body may be sending, you can take timely action to protect your health.
Swelling in an Arm or Leg Without Injury

Swelling in a limb is one of the most common yet overlooked signs of a blood clot. This typically occurs when a clot obstructs blood flow in a vein, causing fluid to accumulate in the affected area. The swelling may start gradually or appear suddenly, often localized to one leg or arm. Although the area might not always be painful, the skin can feel tight or stretched, further adding to the discomfort.
This type of swelling is particularly concerning because it is easy to dismiss as a minor issue, such as overuse or a mild injury. However, when swelling appears without a clear cause, it should raise a red flag. It may also be accompanied by other signs like redness or warmth in the area. Prompt medical evaluation can determine whether the swelling is related to a blood clot and prevent more serious complications.
Sudden Shortness of Breath

Shortness of breath is a symptom that can signal a pulmonary embolism, a serious condition caused by a blood clot traveling to the lungs. This may feel like you can’t catch your breath or as if breathing has become unusually difficult. Some people describe it as a gasping sensation that worsens with physical activity or even at rest. In some cases, this is accompanied by a rapid heartbeat or chest pain, which can intensify over time.
Unfortunately, this symptom is often dismissed as anxiety, mild asthma, or even fatigue. However, shortness of breath that comes on suddenly or worsens without an obvious trigger is a warning sign that shouldn’t be ignored. It can indicate that oxygen levels in your blood are dropping due to a blocked artery. Seeking immediate medical attention can be life-saving in cases where shortness of breath is caused by a blood clot.