Keeping your hand sanitizer nearby in plane lavatories is a well-known tip to avoid picking up nasties, but have you considered the seatback pocket? You should. "Airplanes are notoriously filthy, and they’re cleaned far less frequently than you might think; certainly there is no deep cleaning going on during the short period of deboarding and reboarding that goes on at most airline gates," writes Ed Hewitt at Smarter Travel. That means that germs and remnants of food bacteria from previous travelers' socks and snacks are still there. "While I do recommend checking out the emergency information at the beginning of your flight, avoid too much rummaging around in the seatback pocket if you can help it," says Hewitt.

Getting food poisoning when you're trying new foods abroad is so common, it's practically a punchline. While fear of getting ill shouldn't stop you from trying new foods, you should be mindful of your past experiences and how well your stomach adapts to new environments and cuisines. Sticking to bottled water, thoroughly-cooked foods, hard cheeses, and pasteurized dairy are easy ways to avoid some of the most common sources of food-borne bacteria.

The issue with dietary changes on your holiday is that they can throw your digestion for a loop. Take note of what you're eating and how it differs from what you have at home, and if you think you're not getting the same nutrients, be prepared to stock up. "Supplements and vitamins, including iron pills, can help maintain balance when your diet is insufficient. Also, 'sports bars' such as Balance or Power Bars are excellent, nutrient-packed travel snacks," recommends Smarter Travel. Sticking individual packs of vitamins in your bag can help your digestion stay on track.

If you're the kind of person who has to see 10 sights per day and 11 cities in a week, you're also much more likely to experience sickness while you're on holiday. This also applies to travelers who don't plan properly and always find themselves in a haze of stress because they're lost or might miss their train. "Stress in general tends to weaken the immune system [...] This means that rushing to catch flights and dealing with hectic travel schedules can also play a role in the body’s susceptibility to infection," notes physician Christopher Sanford at Popular Science. Slow down, make less complicated plans, and get yourself to the airport on time, and you'll likely find yourself feeling better for it. Rome wasn't built in a day, and it won't disappear after one either.

You may have plotted your holiday impeccably and given yourself the vacation of your life, but what about the aftermath? While it might be tempting to fly back on the last possible day and head to work the next morning, to maximize your holiday time, it's actually a poor idea for your immune system. "Vacationers often have little to no rest between getting home and returning to work," say experts at Cedars-Sinai Hospital. "Try to give yourself a day or two to recover." That way you get all your holiday washing done — and also relax a little before heading back into work.

If you do get ill, make sure you have proper travel insurance, keep hydrated, and know where to go if you need help. It's always valuable to have guidebooks with hospital and emergency numbers in the back — and don't neglect your normal medications just because it's holiday time.