Deep-vein thrombosis (DVT) is a blood clot that forms in a vein deep inside the leg or pelvis. It can sit like a plug or break off and travel to the lung, so early recognition is lifesaving.

Sudden calf pain is the headline. It feels like a deep cramp or “charley horse” that doesn’t ease with stretching or massage.

One-sided swelling shows up fast. The ankle or whole lower leg puffs, so socks leave a tight groove on the affected leg only.

Warmth and redness appear. Skin over the vein feels hot and looks pink or purplish, like a localized sunburn.

Heavy, tight feeling follows. The leg feels wooden, full, and tired even after short walks.

Visible surface veins may pop. Blue cords bulge as deeper veins are blocked and blood reroutes.

Late alarms include sudden chest pain, shortness of breath, or coughing up blood—clues the clot has traveled to the lung.