When people go to a doctor before an international trip, vaccines usually dominate the conversation.
And while those are important, many of the health problems most likely to derail a trip cannot be prevented with a vaccine: diarrhea, respiratory infections, motion sickness and flare-ups of existing medical conditions — none of which can be headed off with a shot.
The Centers for Disease Control and Prevention estimates that between 43 percent and 79 percent of travelers to low- and middle-income countries become ill during or after their journey.
As an infectious diseases physician who specializes in travel medicine and tropical medicine, I counsel many patients before they leave the country and care for them if they come home sick.
A pretravel visit to the doctor should always end with more than a list of shots. You should know which illnesses you could encounter during your trip, which symptoms you can reasonably handle yourself, which medicines to carry and how to use them, and which warning signs mean it is time to seek care.
Understand the evolving risks
Infectious-disease risks abroad are constantly shifting. A health care provider who works in travel medicine keeps up with these changes so that the guidance you get reflects the latest developments.
Since early 2025, for example, South America has seen yellow fever outbreaks that redrew long-standing risk maps and an unusual hantavirus cluster that spread from person to person aboard a cruise ship. Another tropical disease, chikungunya, flared in new places, including the largest outbreak ever recorded in China. And Fiji declared a fast-growing HIV outbreak.
In my own clinical research with colleagues, I have seen travelers who returned to the U.S. with serious and occasionally fatal infections such as malaria and hepatitis, often after dangerous delays in recognizing what was wrong.
Let your itinerary guide the conversation
Travel health advice is not one-size-fits-all. A week at a Caribbean resort, a safari in East Africa and a month trekking in Nepal carry very different risks.
Even the likely cause of a fever changes with the destination. Dengue is a leading concern after travel in much of Latin America and Asia, while malaria is a particular risk in parts of sub-Saharan Africa. Typhoid and paratyphoid fever loom largest in South Asia.
What you do matters, too — freshwater swimming, visiting caves, animal contact, hiking and staying in remote areas each add their own hazards.
So bring your itinerary to the medical appointment. Tell your physician not just which countries you’ll visit, but whether you’ll be in cities or rural areas, what you plan to do, how long you’ll stay and how easily you could reach a reliable hospital.
When to safely treat yourself
For minor problems, you can plan to treat yourself. Diarrhea is the best example. Depending on the destination and season, it affects an estimated 10 percent to 40 percent of travelers during the first two weeks of a trip. Most cases clear up on their own within a few days, but having a plan makes a real difference.
Ask your doctor what to do if diarrhea develops. Oral rehydration salts help replace fluids when losses are heavy. Loperamide, an over-the-counter antidiarrheal, can reduce how often and how urgently you need a bathroom, but it should not be used on its own when diarrhea comes with a fever or blood in the stool. Depending on your destination and medical history, your doctor may also give you an antibiotic to carry and use only for diarrhea that interferes with your daily activities or is severe.
It’s as important to confirm when to use each medicine as it is to have the drugs on hand. Antibiotics have side effects and can leave you carrying drug-resistant bacteria, so they are best saved for the episodes that truly need them.
The same logic applies to other predictable problems. Someone prone to seasickness on a planned boat trip might discuss meclizine or a scopolamine patch. A traveler flying straight into a high-altitude city such as Cusco, Peru, or La Paz, Bolivia, might discuss acetazolamide, a prescription medicine that helps the body acclimatize and roughly reduces by half the risk of altitude sickness during rapid ascents.
Prep a health kit
A basic travel health kit keeps small problems from becoming big ones. Contents depend on the individual and the trip, but useful items include pain and fever medicine, bandages, antiseptic, oral rehydration salts, loperamide, antihistamine and anything prescribed specifically for your destination.
People with chronic conditions should pack enough of their regular medications for the entire trip, plus extra in case of travel delays. Keep medicines in their original labeled containers, carry them in hand luggage rather than checked bags, and consider bringing a copy of prescriptions along with the drugs’ generic names.
Replacing a medication abroad can be harder than you expect. Drugs may have different names, formulations or availability in other countries, and counterfeit or low-quality medicines remain a problem in some places. Some medications that are routine in the U.S. are restricted or banned elsewhere.
Be wary of popular travel cures
Beware of remedies with better reputations than evidence. Ginger is often recommended for motion sickness, but studies have produced mixed results. Acupressure wristbands for motion sickness do not outperform placebos. And despite their popularity, probiotics are not recommended for preventing travelers’ diarrhea because their efficacy is still unknown.
Coca leaves and coca tea are widely used for altitude symptoms in the Andes, but no strong evidence shows they prevent altitude illness. The same is true of garlic, ginkgo, and vitamin E. “Natural” does not mean effective, or even harmless, particularly if a supplement interacts with a prescription drug.
Know when to seek medical care
Perhaps the most important part of any plan is recognizing when self-care is no longer appropriate.
Seek medical attention for severe dehydration, persistent vomiting, difficulty breathing, confusion, severe abdominal pain or illness that is rapidly getting worse. Bloody diarrhea or diarrhea with a significant fever calls for medical care rather than simply taking an antidiarrheal and carrying on with your trip.
At high altitudes, shortness of breath while resting, confusion or difficulty walking a straight line are warning signs. Severe altitude illness is treated by descending and getting medical care — another cup of coca tea is not an adequate substitute.
Fever after travel to an area where malaria is common deserves special attention. Malaria can turn deadly within hours, so get evaluated promptly and make sure the clinician knows where you have been. Some travel-related infections surface weeks or even months after you get home, which is why your travel history stays relevant long after your suitcase is unpacked.
Leave home with a plan
I encourage travelers to make a contingency plan. Ask yourself: If my flight home were canceled and I had to stay abroad another week, would I have enough medication? If I spiked a fever, would I know when and where to seek care?
International travel will never be risk-free. But preparing for what’s most likely to occur can keep a manageable health problem from becoming a medical emergency.
Physician Andrés Henao is a professor of medicine and infectious disease at the University of Colorado at Anschutz.
This article was produced in collaboration with The Conversation, a nonprofit news organization.
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