Blood Clots

Blood clots are gel-like clumps of blood. Clotting is essential to stop bleeding, but a clot that forms inside a blood vessel when there is no injury can block circulation. Clots in the veins are the most common problem. The National Heart, Lung, and Blood Institute uses the term venous thromboembolism (VTE) for clots in the veins, which include deep vein thrombosis (DVT) and pulmonary embolism (PE). Clots in arteries are a main cause of heart attacks and strokes.

Warning signs of a leg clot include swelling, pain, tenderness, warmth, or redness, usually in one leg. A clot in the lungs can cause sudden shortness of breath, chest pain, a fast heartbeat, or coughing up blood, and requires emergency care. Risk factors include surgery, hospitalization, long periods of sitting, cancer, pregnancy, smoking, obesity, estrogen-containing medicines, and devices placed in the veins.

Blood clots show up in many drug and device cases. Some medicines carry label warnings about clot risk, and lawsuits may argue the warning was missing or too weak. For example, in 2021 the FDA required new warnings about blood clots and other serious risks for the JAK inhibitor Xeljanz. Devices that sit in veins, such as implanted ports and catheters, have been the subject of claims alleging they led to clots.

A clot claim needs medical records confirming the diagnosis, often by ultrasound or CT scan, and records showing when you used the drug or received the device. See our Bard port catheter lawsuit page and our term pages on thrombosis and pulmonary embolism.