One of the healthiest ways to prevent travel-related DVT is to drink plenty of fluids before, during and after your flight. Normal air humidity typical falls within the 40 to 60 percent range, but it’s a measly 15 percent on an airplane. Therefore, passengers can loose comparatively more moisture through breathing and mucous membranes than when they’re on the ground. To prevent your blood from thickening and the vein walls from expanding, drink plenty of fluid — especially water.
As for whether or not alcohol counts as liquid, most experts agree it’s totally fine and does not increase your chances of developing DVT. In fact, some studies have shown that because alcohol thins your blood, it can actually help prevent DVT. Just don’t go overboard (for lack of a better term); alcohol has a much stronger effect high above the clouds than on the ground.