Getting sick in Costa Rica: what visitors actually get

Dengue circulates year-round in Costa Rica, with more cases in the rainy season and in the warm lowlands — Guanacaste, the Pacific coast, the Caribbean and the northern plains. Typical picture: sudden high fever, intense headache and pain behind the eyes, muscle and joint pain, sometimes a rash, three to ten days after exposure. There is no specific antiviral; treatment is fluids, acetaminophen (never ibuprofen or aspirin, which increase bleeding risk) and monitoring for warning signs — persistent vomiting, abdominal pain, bleeding gums, lethargy — which need hospital care.

Zika and chikungunya are also present at lower levels. Malaria risk is very low and limited to a few areas. Prevention is the same for all: repellent with DEET or icaridin, long sleeves at dusk, and screens or air conditioning.

Traveler's diarrhea is the number-one reason visitors need a doctor. Tap water is treated and generally safe in San José and most of the Central Valley; on the coasts and in rural areas, bottled water is the safer choice. Symptoms usually settle in two to three days with oral rehydration. See a physician if there is fever, blood in the stool, more than six loose stools a day, or signs of dehydration — especially in children and older adults. Antibiotics are sometimes indicated, but not by default.

Costa Rica is near the equator: UV index is extreme most of the year, and sunburn plus dehydration is a frequent combination. San José sits at about 1,170 m, which rarely causes problems; the volcano summits (Irazú at 3,400 m, Poás) and the Cerro de la Muerte pass (3,300 m) can trigger mild altitude symptoms — headache, nausea, breathlessness — in visitors who drive up quickly. Descend and hydrate; symptoms usually resolve within hours.

Rip currents cause most tourist drownings in Costa Rica; many popular beaches have no lifeguards. Surfboard impacts, coral cuts and stingray injuries need cleaning and sometimes antibiotics — coastal wounds infect easily. Zip-line, ATV and hiking injuries mostly involve fractures and sprains; motorcycle and car accidents remain the most serious trauma we see. For any fracture or head injury, an emergency physician should decide whether local care is enough or a transfer to San José is safer.

Diabetes, hypertension, heart disease and asthma decompensate on trips: heat, alcohol, a changed diet, forgotten medication. Bring twice the medication you expect to need, a written list of drugs and doses, and message a physician at the first sign of trouble — early adjustment is simple; an admission is not.