Lifestyle

Blood Clots Kill 100,000 Americans a Year. These 5 Symptoms Are the Warning.

By Erica Coleman · July 9, 2026

Approximately 900,000 Americans develop a blood clot in a deep vein each year. Up to 100,000 die from the complications. The most dangerous aspect of deep vein thrombosis is not the clot itself — it is that the symptoms so closely resemble a pulled muscle, a cramp, or simple soreness that most people dismiss them until the clot moves to the lungs.

1. Swelling in one leg — not both

The hallmark of DVT is swelling that appears in one leg only. A pulled muscle doesn’t typically produce visible swelling. Fluid retention from standing or heat affects both legs equally. Swelling concentrated in one calf, one ankle, or one thigh — particularly if it develops over hours rather than gradually — is the single most important distinguishing sign.

2. A dull ache or cramping sensation that starts in the calf

DVT pain is frequently described as a deep, dull ache — not a sharp pain — that begins in the calf and feels like a cramp that won’t release. The pain is persistent. It doesn’t improve with stretching. It doesn’t go away after walking it off. If you have a calf cramp that has lasted more than a day and doesn’t behave like a normal cramp, treat it seriously.

3. Skin that is warm to the touch and red or discolored

The area over the clot often becomes noticeably warmer than the surrounding skin, and the skin color may change — reddish, bluish, or darker than normal. A pulled muscle might produce general soreness, but it does not typically produce localized warmth and color change. If the painful area in your leg is also warm and discolored, the combination is diagnostic enough to warrant urgent evaluation.

4. Pain that worsens when you flex your foot upward

This is called Homans’ sign — pain in the calf when you flex your foot toward your shin. While not definitive on its own, it is one of the clinical tests doctors use to screen for DVT. A pulled muscle typically produces pain during movement at the site of injury. DVT pain triggered by flexing the foot upward is produced by the clot pressing against the vein wall as the calf muscle contracts.

5. Sudden shortness of breath with or without chest pain

If a DVT breaks free and travels to the lungs, it becomes a pulmonary embolism — a medical emergency that kills one in three people before they reach a diagnosis. The symptoms are sudden and frightening: shortness of breath that comes on without exertion, sharp chest pain that worsens with breathing, rapid heart rate, lightheadedness, and sometimes coughing up blood. If you experience any of these — particularly after days of leg pain or swelling — call 911 immediately.

Risk factors that make blood clots more likely: age over 60, recent surgery, prolonged immobility (long flights, bed rest, desk jobs), cancer, smoking, obesity, hormone therapy, and a family history of clotting disorders. If you have one or more risk factors and experience the symptoms above, don’t wait to see if it improves. An ultrasound diagnoses DVT in minutes.