The cramped conditions and long periods of being less active on a flight can cause pain, stiffness or swelling of your legs. Being less active can lead to slow blood flow in your veins which increases your risk of developing a blood clot, known as deep vein thrombosis (DVT). DVTs most commonly form in the legs.

Long-haul flights (defined as those lasting over six hours) subject the human body to a unique environment of low humidity, recycled air, and pressurized cabins, resulting in several common side effects. The most frequent is Dehydration, caused by the extremely low humidity (often under 15%), which leads to dry skin, headaches, and a "scratchy" throat. Jet Lag is the most significant psychological and physiological side effect, as crossing multiple time zones disrupts the body's circadian rhythm, causing insomnia, fatigue, and cognitive fog. Physical symptoms include Muscle Stiffness and Edema (swelling of the feet and ankles) due to prolonged immobility and reduced circulation. A more serious, though less common, risk is Deep Vein Thrombosis (DVT), where blood clots form in the legs during long periods of sitting. In 2026, health experts also emphasize "Airplane Ear" (barotrauma) and gut issues like bloating and gas, as the change in cabin pressure causes air trapped in body cavities to expand. To mitigate these effects, travelers are advised to wear compression socks, drink at least 250ml of water every hour, and perform "seat yoga" to maintain blood flow throughout the journey.