10 Warning Signs of a Blood Clot in the Leg You Should Know

A blood clot in a deep vein of the leg is called deep vein thrombosis (DVT). It can be serious because part of the clot can travel to the lungs and cause a pulmonary embolism (PE). However, about half of people with DVT have no symptoms at all, so symptoms alone cannot rule it out. CDC+1

Possible warning signs include:

Swelling in one leg — particularly when it develops without an obvious injury.
Pain or tenderness — often in the calf or thigh.
Unexplained aching or cramping in the affected leg.
Warmth of the skin over the painful or swollen area.
Redness or discoloration of the leg.
A feeling of heaviness or tightness in the affected limb.
Swelling that is noticeably greater on one side than the other.
Pain that becomes more noticeable when standing or walking.
Tenderness without a clear injury — especially when accompanied by swelling or warmth.
A combination of several of these symptoms — particularly sudden, one-sided swelling with pain, warmth, or discoloration.

These symptoms don’t prove that a clot is present. Muscle injury, infection, and other conditions can look similar, and medical testing—often including ultrasound—is needed to diagnose DVT. CDC

🚨 Watch for signs of a pulmonary embolism

If a leg clot travels to the lungs, symptoms can include sudden difficulty breathing, chest pain that worsens with deep breathing or coughing, coughing up blood, a rapid or irregular heartbeat, lightheadedness, or fainting. These require immediate emergency medical attention. CDC+1

Risk is higher after recent surgery or hospitalization, prolonged immobility or long-distance travel, certain cancers, pregnancy/recent childbirth, estrogen-containing medicines, previous blood clots, and increasing age, among other factors. CDC+1

Don’t massage a leg that you suspect may have a DVT or try to treat it yourself. Get medical evaluation promptly.