Q: I travel extensively for work and also have varicose veins. Am I at risk for blood clots? What symptoms should I watch for? A: The relationship between travel and blood clots has been studied since the 1950s. The actual risk is difficult to determine but for short trips (<4 hours) there is essentially no risk. For longer trips (>4 hours) there is a slight increased risk for blood clots whether traveling by air, car, bus or train. The primary reason seems to be immobility