You’ve spent hundreds, perhaps thousands of dollars planning your upcoming vacation. The last thing you want is to be laid up in the hotel room – or worse, hospital – missing out on llama trekking, sunset gazing, mescal sipping and other adventures around the world.

While you can’t live in an anti-bacterial bubble, you can take steps to prepare for your trip and stay healthy while on the road. Travel-medicine specialists focus on just that: They’re available to provide immunizations, answer questions about health and safety risks, discuss mosquito-borne diseases that could cause problems and share advice on how to avoid the dreaded diarrhea – the top illness for travelers.

David L. Roque, a family-medicine physician and travel-medicine specialist at Swedish Covenant Hospital and Roque-Ponton Medical Group S.C. in Chicago, weighed in on how to stay healthy on your next adventure. (This interview was edited for brevity and clarity.)

Q: A family is planning a trip. At what point should they seek medical advice?

A: Ideally, a pre-travel consult should take place at least four weeks prior to departure. Some vaccines start kicking in after two to four weeks, so you want to get optimal protection.

Q: What else happens during a pre-travel consult?

A: We’re going to assess not only the risk they have for their destinations but also what are their pre-existing risks. If there’s any medical conditions, we also address that. And then we go on to what medication they’re taking, because there might be some medication that’s interacting with whatever we might give, for instance, for malaria. It’s very helpful when they bring their itinerary, so I can easily and accurately give them advice on the list they have on those destinations.

Q: What advice are you giving regarding Zika?

A: For travelers to endemic areas for Zika, we tell them to avoid pregnancy for at least eight weeks for women, but if the couple, including the male partner, comes in, we have to tell them to wait at least six months after departure from the endemic area (before conceiving).

Q: If people are going to an area with mosquitoes, what should they take?

A: I always advise them to use an insect repellent containing DEET. DEET is the safest,well-studied insect repellent. It has to contain at least 30 percent or higher of DEET – there’s no need to use more than 50 percent – and they have to apply it every four hours to exposed parts of their body. If you use less than 30 percent, you need to apply it more often. There’s one brand that I recommend, because I look at all these products, and it’s Coleman.

Q: What’s the rule of thumb for eating and drinking on the road?

A: When you’re traveling, you should only eat fully cooked, hot, steaming food. That means avoiding salads or raw vegetables, because those are the most common cause of E. coli infections. (In developing countries) all liquids – not just water – have to come from a sealed container. That includes India, Southeast Asia and all developing countries. Because when you drink tap water, that’s how you can get exposed to contaminants. You can eat as much fruit as you want, as long as you do your own peeling. If the fruit has been peeled by someone else, I would not touch it. The culture of hand-washing in certain destinations is very poor. Those are the things that travelers should know, because traveler’s diarrhea is the No. 1 cause of illness (for travelers).

Q: What do you tell patients to do if that happens?

A: When patients come to see me (before traveling), I usually prescribe an antibiotic to make sure when they come down with diarrhea they can start self-treatment. Traveler’s diarrhea can get better on its own, but it can get worse to the point where they cannot hold down anything. And if that happens, they would need an IV antibiotic and IV fluids. So I usually tell patients, the moment you start having the diarrhea, you start taking the antibiotic. If you get worse by day three, it’s too late. The antibiotic will not work because you can’t hold down anything. Depending on destinations, in Southeast Asia, Cipro does not work anymore against those common pathogens that cause traveler’s diarrhea. So if a traveler is going to Southeast Asia, the only (antibiotic) that works right now is azithromycin. A lot of travelers are not aware of that because primary-care doctors like using Cipro. But in Southeast Asia, it’s not going to work.

Q: What about street food?

A: A lot of travelers will ask me if it’s safe to eat from street vendors, because most of those street vendors, they have the best food, and when you travel you want to experience culture. There are two rules, and if street vendors meet those two rules you can eat from street vendors: the food you’re about to eat has to come from charcoal or a stove and served hot and steaming; and you have disposable utensils. When I travel with my family, we bring our disposable utensils, so when we see food that looks good, if it’s coming from charcoal or a hot stove, we just tell them to put it on our disposable utensils, so it’s easy to dispose of after you’re done eating.

Q: Any tips for staying healthy when you’re in transit?

A: The dirtiest part of the plane is your tray. Use disinfectant, like wipes, on your tray table before touching it, and also use wipes on the armrests. And of course, always use hand sanitizer.

Q: What are some items you should always take when you’re traveling?

A: Whenever a traveler comes to me, I always tell them to bring the most common medications that you might need. For instance, like Tylenol, you should always have that with you, and a motion-sickness pill, especially if you’re doing a lot of seafaring activity that might make you sick. There should be two sets of medication, because if you put everything in your carry-on or your checked bag, you could lose your medication if you lose your luggage. I tell them to divide your medications and put half and half [in each bag].

Q: Do you have any jet-lag tips?

A: The best way to avoid jet lag is keeping yourself hydrated and avoid alcohol and caffeine-containing beverages. Traveling west to east is worse than coming back east to west. So I tell them to drink a lot of water and adjust your time as if it’s your destination time. Try to get sleep if it’s nighttime at your destination. There’s really nothing much we can do about jet lag.

Q: What else can you share?

A: I always advise travelers to pack your common sense. A lot of Americans get in trouble in foreign destinations because they get drunk. So I tell them don’t get drunk, especially if you’re by yourself, because that’s how you can get taken advantage of. I always remind them that it’s not a complete stranger who might victimize you, it’s someone that you had contact with already, so don’t be too trusting. That has happened in a lot of crimes that happen to Americans. And for high school travelers who stay in local homes, I tell them if you’re by yourself in the house, lock yourself in your room. If you’re a woman, don’t stay with a male host. Those common-sense tips are more important than anything else we talked about.