The amount of radiation is minuscule, and jet lag can usually be overcome in a few days. But for anyone flying dozens of times per year — say, at least two cross-country flights per month — these stresses start to add up, putting frequent fliers in higher risk categories for cancers and other chronic health issues.

There is no magic number of flights that is officially "unhealthy," but medical research into "Frequent Flyer Syndrome" suggests that taking more than 20 to 30 long-haul flights per year can have measurable impacts on physical and mental health. The primary health risks associated with excessive flying include chronic jet lag, which disrupts the circadian rhythm and can lead to weakened immune systems, digestive issues, and cognitive decline. Frequent exposure to the dry, pressurized cabin air (with humidity often below 10%) can cause chronic dehydration and respiratory irritation. More seriously, "ultra-frequent" flyers are at a higher risk for Deep Vein Thrombosis (DVT) due to prolonged immobility and slightly higher exposure to cosmic radiation at high altitudes—though the radiation risk only becomes significant for flight crews or those flying hundreds of thousands of miles annually. Mentally, the "burnout" from constant travel, hotel living, and social isolation can lead to increased anxiety and depression. For the average person taking a few trips a year, flying is perfectly safe; however, for "road warriors," experts recommend prioritizing movement during flights, aggressive hydration, and allowing for "buffer days" to recover between time zone shifts.