Air travel’s surprising effects on the body—and how to cope

Air travel can stress the body through cabin pressure and low humidity, which loads the heart and lungs and can cause dehydration that thickens the blood and raises clot risk. Fainting from postural changes and gas expansion in the gut (jet belly) can occur, while rare in-flight cardiac emergencies have poorer outcomes due to limited onboard care. To mitigate risks: stay hydrated, take medications on schedule, move around every couple of hours, limit alcohol, and be cautious after recent dental work or diving; flight crews decide if and when to land in an emergency.