Yellow fever vaccination is required or strongly recommended for travel to the Amazon basin and surrounding lowland areas in Brazil, Peru, Bolivia, Colombia, and Ecuador. Some countries will ask for proof of vaccination if you're arriving from an affected area. Get the shot at least ten days before you travel — it's a single jab that lasts a lifetime. Carry the yellow WHO vaccination card with your passport.
Malaria is a real risk in jungle regions, particularly the Amazon lowlands and parts of rural Venezuela. If you're heading into the jungle — whether for an Amazon lodge, the Pantanal, or trekking in lowland Bolivia — talk to a travel doctor about prophylaxis. Dengue fever and Zika are mosquito-borne and present throughout tropical lowlands across the continent. There's no prophylaxis for these; your best defense is covering up at dusk and using repellent with DEET.
Altitude sickness catches people off guard. La Paz sits at 3,640 meters, Cusco at 3,400, and Quito at 2,850. If you fly directly to any of these from sea level, expect headaches, shortness of breath, and fatigue for the first day or two. Take it very easy on arrival — no big hikes, no heavy meals, drink plenty of water. Coca tea helps and is widely available in the Andes. If symptoms get severe (confusion, persistent vomiting), descend immediately. Consider spending a night at an intermediate altitude when possible.
Tap water is not safe to drink in most of South America. Stick to bottled or filtered water, and be careful with ice in drinks outside of tourist restaurants. Street food is generally fine if it's freshly cooked and the stall is busy — a high turnover means fresh ingredients. Chile, Argentina, and Uruguay have the safest water and food hygiene on the continent, though bottled water is still the default for travelers.
Get good travel insurance before you go — the kind that covers emergency evacuation, not just hospital visits. Medical care in major cities like Buenos Aires, Santiago, and Sao Paulo is excellent, but remote areas have limited facilities. If you're trekking at altitude, visiting the jungle, or doing any adventure sports, make sure your policy explicitly covers those activities. Pharmacies across the continent are well-stocked and often sell medications over the counter that would require a prescription at home.