For high-risk individuals,

For high-risk individuals, the chance of a severe pulmonary embolism (PE) on a long flight is still very low but significantly elevated compared to the general population, possibly around 5% per long-haul flight for those with multiple risk factors. Risk factors include cancer, heart/lung disease, a previous blood clot, obesity, and inherited clotting disorders. While the absolute risk is small, the relative risk is substantially increased for high-risk groups, highlighting the importance of consulting a doctor before travel.