After a long flight, it's normal to feel bloated. This is because sitting for extended periods of time can cause gas and fluid retention. Bloating usually lasts for a few hours after flying, but can linger for up to a day or two. To help reduce bloating, drink plenty of fluids during the flight and move around as much as possible. Avoiding salty foods and carbonated beverages can also help. If you're still feeling bloated after a couple of days, try over-the-counter medications like simethicone or probiotics.