Traveler’s Diarrhea 

If you’ve ever talked to someone who’s backpacked through South America or Southeast Asia, chances are you’ve heard about traveler’s diarrhea. It’s not glamorous, but it’s one of the most common health issues abroad. The causes range from bacteria like E. coli and Salmonella to parasites such as Giardia or viruses like Norovirus.

High-risk areas include India, Mexico, Thailand, and Egypt, but it can strike almost anywhere. The problem is that your digestive system isn’t used to the local bacteria, and something as simple as rinsing fruit in tap water can be enough to trigger an infection. Many travelers underestimate how easily it spreads—ice cubes in your drink, brushing your teeth with tap water, or grabbing a bite from a food cart all carry some risk.

Prevention requires discipline. Sticking to bottled or boiled water, avoiding raw produce, and being cautious with street food can cut your chances significantly. The saying “boil it, cook it, peel it, or forget it” has been around for decades because it works. But even with careful habits, mistakes happen.

When it comes to treatment, the difference between over-the-counter and prescription options really shows. Rehydration salts and loperamide may help you get through a long bus ride, but they don’t cure the infection. Prescription antibiotics, like azithromycin, are the first-line treatment in much of Asia because resistance to other drugs is rising there. 

Ciprofloxacin or metronidazole may be used in other cases. Having one of these on hand before you travel can make the difference between losing a day to an upset stomach and losing an entire week of your trip.

Scabies

Scabies might not be as widely discussed as traveler’s diarrhea, but for those who catch it, it can be miserable. Caused by tiny mites called Sarcoptes scabiei, scabies spread through skin-to-skin contact or contaminated bedding. Mites burrow under the skin, leading to intense itching—often worse at night—and a rash that can include small bumps or burrow marks.

Where do scabies show up for travelers? Crowded areas like long train rides where bedding may not be washed between passengers. Group housing and shared clothing situations also raise the risk. Backpackers, budget travelers, and anyone moving between shared accommodations should keep it on their radar.

If an outbreak is circulating where you’re staying, it’s very easy to be exposed without realizing it. That’s why grabbing prescription-strength options like permethrin cream or oral ivermectin tablets ahead of time is a great idea to reduce your risk. For travelers, having these medications before you leave means you won’t be stuck waiting for access to a doctor in another country if scabies shows up during your trip.

Parasitic Worms

Parasites are a less visible but equally significant risk. In regions such as Sub-Saharan Africa, South Asia, and Latin America, intestinal worms like hookworms, roundworms, and tapeworms are widespread.

Transmission usually happens in ways travelers don’t expect. Walking barefoot through contaminated soil can expose you to hookworms. Eating undercooked meat may lead to tapeworm infection. Even something as simple as drinking untreated water can put you at risk for parasites that stay in your system long after your trip is over.

The challenge is that symptoms don’t always show up immediately. You might not feel sick until weeks later, making it difficult to trace the infection back to a specific meal or activity. Some parasites cause abdominal pain, diarrhea, or fatigue, while others may linger quietly before causing more serious health issues.

Parasites can be stubborn, and even the most careful traveler can get exposed. That’s why having access to prescription deworming medications such as albendazole or ivermectin is essential. These medications have been shown to be effective against most intestinal parasites and can potentially save you from long-term health complications or a ruined trip.

Malaria

Malaria is one of the most well-known travel risks, and for good reason. Spread by the bite of the Anopheles mosquito, malaria remains a serious threat in tropical and subtropical regions. Sub-Saharan Africa carries the highest burden, but parts of India, Southeast Asia, and South America are also affected.

The symptoms can look like the flu at first—fever, chills, sweating, and fatigue—but malaria is far more dangerous if untreated. It can progress quickly, becoming life-threatening in a matter of days. This is not an illness you can “wait out.”

The good news is that prevention works. Sleeping under insecticide-treated bed nets, applying repellents with DEET, and wearing long sleeves at dusk and dawn dramatically reduce the risk of mosquito bites. The most important step, however, is taking prescription malaria pills such as atovaquone-proguanil before and during your trip. These medications act as a shield, preventing the infection from developing in your body even if you’re bitten.

If a malaria infection does occur, treatment involves artemisinin-based combination therapies (ACTs), which are effective but not easy to access while traveling. For that reason, prevention is often the best strategy.