From the Guidelines
Crossing your legs while sitting does not significantly increase the risk of blood clots for most people. While prolonged leg crossing may temporarily reduce blood flow and cause numbness or pins and needles, it typically doesn't create the conditions necessary for dangerous blood clots to form. The real risk factors for blood clots (deep vein thrombosis) include prolonged immobility such as during long flights or hospital stays, certain medical conditions like cancer or heart failure, recent surgery, pregnancy, hormonal medications, obesity, smoking, and genetic factors. According to the American College of Chest Physicians evidence-based clinical practice guidelines 1, the focus for preventing VTE should be on frequent ambulation, calf muscle exercise, or sitting in an aisle seat if feasible, especially for long-distance travelers at increased risk of VTE. Some key points to consider include:
- Prolonged immobility is a significant risk factor for blood clots
- Certain medical conditions, such as cancer or heart failure, increase the risk of blood clots
- Recent surgery, pregnancy, hormonal medications, obesity, smoking, and genetic factors also increase the risk of blood clots
- Staying hydrated, taking breaks to walk around during long periods of sitting, maintaining a healthy weight, avoiding smoking, and discussing personal risk factors with a healthcare provider are more important preventive measures. For those with existing circulation problems or high risk for blood clots, changing positions frequently and avoiding prolonged leg crossing may be beneficial, but occasional leg crossing during normal daily activities is not a significant concern for most healthy individuals.
From the Research
Blood Clots and Leg Crossing
- There is no direct evidence in the provided studies that crossing your legs when sitting causes an increased risk of blood clots 2, 3, 4, 5, 6.
- However, a study found that crossing legs at the knee during blood pressure measurement increased systolic blood pressure significantly by 6.7 mmHg in hypertensives and 7.9 mmHg in treated diabetics 3.
- Another study suggested that estrogen increases the risk of both arterial and venous thrombosis, but it does not mention leg crossing as a factor 4.
- The other studies discuss the risk of thrombosis associated with hormone replacement therapy and contraceptive choices, but do not address the specific question of leg crossing 2, 5, 6.
Related Factors
- The risk of venous thrombosis is influenced by various factors, including hormone replacement therapy, estrogen dose, type of progestin, and presence of thrombophilia 2, 4, 5, 6.
- Increasing age, being overweight, and recent surgery are also associated with a higher risk of venous thrombosis 2, 5.
- The route of administration of estrogen, such as transdermal or oral, can also affect the risk of thrombosis 2, 5.