Deep vein thrombosis (DVT) is a serious but preventable medical condition that affects as many as 900,000 people every year in the U.S. DVT occurs when a blood clot forms in one of the veins located deep inside the body. Though DVT can occur in other parts of the body, such as the arms, it usually involves the veins in the lower leg, pelvis and thigh. DVT is a dangerous condition. The blood clot can break off and travel through the bloodstream to an artery in the lungs and block blood flow, which is called a pulmonary embolism. This can lead to illness, disability or even be fatal if not treated right away. However, DVT is treatable if discovered early. Understanding the symptoms and risk factors for DVT can better prepare you to take appropriate actions if needed. Your doctor can help you identify and manage your personal risk factors to lessen your chances of having DVT. What are the symptoms of DVT? DVT can happen to anyone, so knowing the symptoms could save your life by alerting you to get medical help right away. While about half of those experiencing DVT have no symptoms at all, these are some of the signs to look for: Skin that is warm and red Swelling in the leg or arm Unexplained tenderness or pain Difficulty breathing Fast or irregular heartbeat Dizziness or fainting What are the risk factors for DVT? Many people have at least one risk factor for DVT. The most common risks include being over 40, a previous personal history or family history of blood clots, obesity, and smoking. DVT is also associated with limited mobility, such as having a limb in a cast or being in one position for a long time, such as being confined to bed or sitting in an airplane for an extended flight. Additional risk factors include: Hormone replacement therapy Use of a catheter in a central vein Pregnancy and the six weeks after delivery Surgery or injury within the last three months Use of contraceptives containing estrogen Chronic medical conditions such as cancer, heart disease or inflammatory bowel disease How can I prevent DVT? If you are at risk, your doctor can recommend treatments like medical compression stockings and medications, and help you address your risk factors. Lifestyle tips for avoiding DVT include moving around as much as possible after being confined to bed or when traveling for four hours or more on an airplane, and performing leg exercises while sitting. If you experience symptoms of DVT, seek care immediately.