It’s not like you don’t already have a lot to deal with when you fly: delays, overbooked flights, TSA rules, snakes in the cabin — well, maybe not the last one. But flying is filled with inconveniences, expected and not. And, enclosed in a capsule at 35,000 feet, health concerns abound. With adequate knowledge and preparation, though, you can stay healthy on a plane.

See also: Avoid these 5 trip ruining travel diseases in the U.S.

Stay healthy on a plane by stretching, even if you're seated. — Photo by Lluís Real/Age Fotostock

First, know your limits: if you have a critical illness, are suffering from an active infection or have had recent surgery, you shouldn’t fly. Second, know that the crew is trained in basic emergency measures, such as CPR, and that most commercial planes have a well-stocked medical kit that can be used by trained medical personnel who happen to be aboard. (I have assisted medically on many flights and have used this kit’s advanced medications and IVs to stabilize critically ill passengers.)

Third, know how to avoid getting sick. Here are a few air-travel conditions that you can alleviate or prevent.

1. Deep venous thrombosis
We’ve all heard about these deadly blood clots, but what are they? Related primarily to immobility for a prolonged period of time, DVTs occur when blood pools and then clots in deep veins of the legs. The real danger is these clots breaking off and traveling to the lungs. Certain things increase your risk of DVT, among them chronic medical conditions, previous blood clots, cancer and obesity.

So what to do? Stay as active as possible. Even while sitting in your cramped seat, there are leg exercises you can do to increase circulation. When the captain says it’s safe to move around the cabin, then, do! If you’re on a very long flight, do so more often. Compression stockings or socks can also help prevent clots, as can staying hydrated and avoiding alcohol and caffeine.

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