Any long-distance journey lasting four hours or more doubles a traveler’s risk of a venous thrombosis or blood clot, no matter whether the travel is by plane, car, coach or train. Some studies show that for healthy people, the risk of a blood clot within a deep lying vein such as in the calf or thigh is quadrupled with air travel. Longer flights carry the greatest risk. For flights lasting more than four hours, the risk of a deep vein thrombosis dramatically increases to one event per 4,656 flights. For flights lasting 16 hours or more, the risk is one event per 1,264 flights.
The symptoms of DVT can include tenderness and redness in the affected area as well as swollen, painful legs, especially if one leg is more affected than the other. Another symptom can be discoloration of the affected area due to poor blood flow. Fever can indicate a DVT.
Sometimes the first indication of a travel-related DVT is a piece of the clot breaking off and traveling in the blood stream to the lungs and causing a pulmonary embolus.
An embolus can cause the lung to collapse or lead to heart failure. Symptoms such as stabbing chest pain and shortness of breath may not occur for several days or even weeks after the DVT initially formed. Someone with these symptoms, whether or not he or she has traveled within the previous eight weeks, should seek immediate medical attention.
