Dr Joseph Mulvehill, MD, a New York-based physician who specializes in travel medicine, notes that “people often transpose their own healthcare template onto that of the country they’re visiting.” In fundamental nature travelers assume things will be quick and easy — this is rarely the case. No one wants to waste precious time seeking out a suitable doctor, followed by hours holed up in a waiting room, just for the sake of an impromptu examination or prescription. “Travelers from comparatively clean countries like the US are far more likely to fall ill,” says Dr Mulvehill. “We live in a relatively germ-free world, so when we travel our bodies react far quicker to the different bacteria.”

Don’t Adjust Your Watch for Short Trips

It takes four to five days for East Coasters to adjust to West Coast time and vice versa. “Jet lag is the biggest travel health pitfall elite athletes’ face. When they head across time zones for just a couple of days, they don’t even try to adjust,” says Dr. Wroble. Changing routine for short trips can equal exhaustion in both directions. If your stay is brief—and only two or three time zones’ difference—schedule activities on your own time zone (lest an 8 a.m. breakfast meeting actually feel like five in the morning).

Don’t Test Your Meds on the Road

With your body as a testing ground for a fistful of unfamiliar medication the moment you board the plane is a recipe for disaster. “In the past one possible side effect of malaria prophylaxis was that it caused terrible nightmares. They were very vivid and sometimes quite horrific nightmares. People couldn’t tolerate them so they stop taking it,” says Dr. Mulvehill. Start taking your meds before you leave so you can seek alternatives if you suffer side effects.

Don’t Vaccinate Too Late

“Only about 30 to 40 percent of people who should be immunized actually are, ” states Dr. Coward. Also, don’t forget that many vaccines like hepatitis and yellow fever aren’t active for two weeks or more so don’t ask the doctor for a jab the morning of your flight. “What people need to realize is that most of the basic vaccinations, once you’ve had them, cover you for many years of future travel—yellow fever lasts ten years,” explains Dr. Mulvehill.

Coast residents swapping a surfboard for a snowboard should beware of vigorous sports after changing altitude. “No one listens,” says Dr. Wroble. “They say, ‘What are you telling me: not to ski?’ If you go from L.A. to Colorado your blood is not used to higher altitude and won’t be able to carry as much oxygen. Particular if you’re older or not in good health, you should take it easy for the first couple of days.”

Don’t Ignore Your Mother

At 40,000 feet above the earth you’re sharing recirculated air with 450 fellow passengers (even if, in theory, fresh air from outside can be brought in and reheated, in practice the cost of doing so means you can assume the cabin air isn’t the freshest). Says Dr. Jana, “It’s simply a numbers game—you’re more likely to catch cold. Of the 50 people before you who used that moving sidewalk in the airport, twelve probably blew their nose and didn’t wash the hands. For adults that means don’t touch it—and for kids, don’t touch or lick it. Wash your hands frequently to avoid transferring infection.

Don’t Get Dehydrated

“The most overlooked health pitfall while travelling is dehydration,” says Dr. Mulvehill. “In August most New Yorkers only go outside when they have to but tourists walk about all day in the heat. Make sure you drink bottled water, especially if you’re in direct sun like on safari or standing in long lines,” he says, adding that it’s important to crack the seal in suspect countries to make sure the bottle hasn’t just been filled with tap water.

Be Careful of Fruits And Vegetables

“After receiving vaccinations, people often make the mistake of feeling bullet-proof,” warns Dr. Coward. “I tell people that 20 percent of staying healthy is getting the vaccination and 80 percent is following good food handing techniques.” That means, for travelers heading to at-risk destinations, don’t swallow shower water, don’t brush in tap water, be wary of ice in drinks and (according to Dr. Mulvehill) whatever you do, watch out for fruits and vegetables, especially if you’ve bough it from a street vendor. “If you peel it yourself it’s probably clean. If it’s all cut up in a bowl it might easily have been contaminated by dirty knives and cutting board. No one considers fruit salad a danger, but it is.”

Don’t Forget a Doctor’s Note

By all means decant your meds into a SMTWTFS pillbox but don’t forget a note from your doctor describing exactly what differentiates the blue from the red ones. “If you’re taking Vicodin you had better be ready to answer why you have it. If possible, carry the pills in the bottle that has the prescription taped to it along with your physician’s number and address,” recommends Dr. Wroble

Never Mind Malaria, Avoid Dengue Fever

“I probably spend more time convincing people that they don’t need anti-malaria medication than convincing them that they do. For many travelers taking malaria tablets is almost a Rudyard Kipling-style rite of passage. In reality people are almost five times more likely to contract dengue fever,” says Dr. Coward, adding, “By far the most likely thing to injure a tourist overseas—and we’re talking 60-70 percent of all injuries and ailments—is a motor vehicle accident. Be very careful of traffic and make sure you’re adequately insured.”