No matter how many times someone travel, some people always feel sick after a trip. Even for seasoned travelers, there are several steps you can take to keep your immune system up to par and germs and bacteria at bay.
My number one piece of advice for staying healthy is to use common sense: Wash those hands, pack your vitamins, take it easy on the booze, don't overdo it if you start to feel run down, and no matter how delicious a certain comestible may look, play it safe and watch what you eat.
There are also a few suggestions specific to air travel and hotels to consider:
Squirt a bit of saline solution or any sort of "nasal mist" up your nose. You can do this before boarding a flight to help keep your nose moist and capable of warding off microorganisms circulating around the bone-dry cabin, courtesy of that guy hacking up his lungs sitting behind you. Re-squirt midflight, particularly if you're surrounded by kids and coughers and forgot to pack your pandemic mask.
Hydrate like there's no tomorrow. The last time I checked (although things could have changed), most major domestic airlines don't charge for those mini bottles of water. When the flight attendant comes around, politely ask for two. Hot, antioxidant-rich tea is a fine idea as well. If you're a nervous flyer like me, that beneficial H2O-guzzling mixed with a hummingbird-like metabolism means lots of trips to the WC, so consider booking a seat on the aisle for easy in-and-out access (and to avoid sitting next to the window area that folks have breathed/sneezed all over). Besides, getting up for a stretch and a tinkle when the fasten seat belt sign is off will improve circulation. And on the topic of air-travel related jitters, look into ways to naturally soothe them since the more wound-up/stressed-out you are, the more likely you are to get sick due to a weakened immune system.
Bring your own pillow or blanket. Although some airlines like JetBlue and American Airlines sell pillows and blankets instead of reusing them, I highly recommend going the BYOP route to avoid snuggling up with something that some guy on the flight from Denver used as a Kleenex. If you don't bring your own blanket and/or pillow and your flight (most likely an international one) doles them out free-of-charge, make sure that it's wrapped in plastic, ensuring that it's either new or has been washed.
Pray that you aren't delayed on the tarmac for an exorbitant amount of time. According to The Wall Street Journal, the air quality of grounded planes is worse than when it's cruising above the Earth and the powerful air circulation systems are in full operation. Says Byron P. Jones, chairman of an American Society of Heating, Refrigerating and Air-Conditioning Engineers that studied air quality on airlines: "If you have it [a plane's air circulation system] off even five minutes, you start to build up contaminants in aircraft." No big surprise here if you've ever been stranded on a hot and stuffy plane for hours on end. The only way to really avoid sitting in germy runway gridlock is to avoid super-busy travel departure times like the early morning and the late afternoon/early evening and anytime around the holidays.
Invest in an arsenal of natural, thyme oil-based disinfecting wipes or spray and use liberally. And I don't just mean on the plane after using the bathroom or flipping through the SkyMall catalog but in the airport (it helps to think of them as hospitals with long lines and a Chick-fil-A around every corner) and after using taxis, airport shuttle services, public transportation etc. Traveling is an extremely hands-on experience, so take the time to ensure that your paws are microbe-free after all that surface touching. Once in your hotel room, you can lay off the hand sanitizers a bit, but remember to take advantage of those delightful complimentary soaps and hot water. You never know who fiddled with the light switches, remote controls or ice bucket before you.
Check in to a hypoallergenic hotel room. After sitting on a virtually humidity-free airplane for six hours, your respiratory system may be on high alert. In addition to paying mind to the health of Mother Nature, many major hotel chains such as Hyatt now offer special rooms with improved indoor air quality that cater to those suffering from allergies, asthma and respiratory ailments. This isn't to say that an "allergy-friendly" hotel room will rid you of the cold virus you caught en route from SFO to DTW, but an allergen-free room will help your body from going further out-of-whack.
I think this covers the basics! Happy and healthy travels!