Deep Vein Thrombosis (DVT) is often referred to as the “economy-class syndrome” because it can flare up during long airplane flights with cramped seating arrangements. But you don’t have to travel across the world to be at risk.

DVT is a blood clot that forms deep within the vein, most frequently in the legs. Symptoms of pain and swelling are not always apparent because DVT forms so deep in the vein. Risk factors include: being inactive for long periods of time (such as after surgery or an illness); having an inherited blood clotting disorder; being pregnant, overweight or over 50 years of age; and having varicose veins.

The condition is common and, occasionally, life-threatening. If the clot breaks loose and travels through the bloodstream, it can block an artery in the lungs. This is called a pulmonary embolism, the most serious complication of DVT.

People at risk should take the following steps to prevent DVT: