Two simple things make airplanes the perfect germ companion: the air is being recirculated and you are in close proximity to others. The other creepy thing to remember about airplanes is that viruses can survive for short periods in the air and on the surfaces like tray tables, seat backs and arm rests of airliners
1) If you have nasal congestion or ear pain before getting on your flight consider a Sudafed 30 minutes before takeoff to avoid that painful ear pressure upon takeoff and landing
2) Use a saline nasal spray (2 sprays in each nostril) 30-60 minutes before your flight. Most cold viruses enter through your nose and dry, cracked mucosa in your nose are a PERFECT entry site for those viruses. Your goal is to keep the mucosa MOIST.
3) Take the Water! For prevention of a dry throat and nose stay hydrated . Airlines are pretty good about passing out water and think of it as your marathon and TAKE THE WATER. Avoid caffeine and alcohol because they are diuretics and will add to the dehydration. Again, dry cracks in the nasal passages are a haven for cold viruses and that is their favorite place of entry.
4) The dreaded clot in the leg: If you are on a flight 5 hours or longer you are at increased risk for a DVT (deep venous thrombosis) which can travel to your lung .Ideally book a seat in an exit row, a bulkhead seat, or an aisle seat. Walk up and down the aisle about once an hour or flex your ankle up and down like you are pushing on the accelerator. Why do this craziness? Blood pools in the veins in your leg when you are sitting in cramped quarters ("economy class syndrome") so your job is to get things moving. Consider a baby aspirin the morning of your flight for prevention as well.
5) Can't touch this: There are many contaminated surfaces on planes. We as physicians call those "Fomites". As gross as the blankets and pillows on airplanes may seem the FAA actually found they aren't all that bad because they are washed but the trays, overheads, etc. are not. The area to worry about on airplanes are the galley water taps and lavatory faucets where they have found germs associated with feces (butt bugs) in 17% of airplanes tested.
6) An ounce of prevention: Your best weapon against those germs is washing your hands. Here is the all-star guide to hand washing: use soap and warm water and rub hands together (the friction may be the reason hand washing really works) for 15-20 seconds....the length of Happy Birthday twice or your ABCs once.
7) Extra credit! This goes to those who use an alcohol based antibacterial hand gel AFTER washing their hands.
8) Should I give it a wipe down? There is no evidence for this but some would suggest using an alcohol-based disposable hand wipe to wipe the trays, overheads, and armrests before you touch them.
9) I've got to get some sleep: The popular atypical benzodiazepines (Ambien, Sonata, Lunesta) are commonly used for sleep on plane flights. A word of caution about these: Ambien CR and Lunesta are longer acting (think 6-8 hours) so you may need to be carried off the plane if you take them for a 3 hour flight.