Health

Tap water should be avoided at all times.  Drink only water that comes from a bottle and try to avoid drinking beverages with ice in dubious places.  Also beware of uncooked fruits and vegetables which may have been washed with tap water.  Most homes and restaurants will wash their fruits and vegetables with disinfectants but some restaurants are not as cautious.  When in doubt, hold back on the salad. 

Also beware of mayonnaise that has been cooked in home-made type restaurants.  Home-made mayonnaise is made with raw egg and can be infected with salmonella.  It is recommended that you stay away from the varieties of ceviches or tiraditos that are made with sauces, rather than just the classic version made with lime.  These sauces, sometimes mayonnaise based, are known to carry with them upset stomachs.

Medications
Altitude sickness (‘soroche’) may occur in travelers who ascend rapidly to altitudes greater than 2500 meters, including Cusco (3000 meters) and Lake Titicaca (4000 meters). Acetazolamide is the drug of choice to prevent altitude sickness. The usual dosage is 125 or 250 mg two or three times daily starting 24 hours before ascent and continuing for 48 hours after arrival at altitude. Possible side-effects include increased urinary volume, numbness, tingling, nausea, drowsiness, myopia and temporary impotence. Acetazolamide should not be given to pregnant women or those with a history of sulfa allergy. For those who cannot tolerate acetazolamide, the preferred alternative is dexamethasone 4 mg taken four times daily. Unlike acetazolamide, dexamethasone must be tapered gradually upon arrival at altitude, since there is a risk that altitude sickness will occur as the dosage is reduced.  Travel to high altitudes is generally not recommended for those with a history of heart disease, lung disease, or sickle cell disease.

More natural preventatives for 'soroche' include drinking coca leaf tea, eating lightly and taking it easy for a day or two while your body gets acclimatized to the altitude.

Travelers' diarrhea is the most common travel-related ailment. The cornerstone of prevention is food and water precautions, as outlined below. All travelers should bring along an antibiotic and an antidiarrheal drug to be started promptly if significant diarrhea occurs, defined as three or more loose stools in an 8-hour period or five or more loose stools in a 24-hour period, especially if associated with nausea, vomiting, cramps, fever or blood in the stool. A quinolone antibiotic is usually prescribed: either ciprofloxacin (Cipro)(PDF) 500 mg twice daily or levofloxacin (Levaquin) (PDF) 500 mg once daily for a total of three days. Quinolones are generally well-tolerated, but occasionally cause sun sensitivity and should not be given to children, pregnant women, or anyone with a history of quinolone allergy. Alternative regimens include a three day course of rifaximin (Xifaxan) 200 mg three times daily or azithromycin (Zithromax) 500 mg once daily. Rifaximin should not be used by those with fever or bloody stools and is not approved for pregnant women or those under age 12. Azithromycin should be avoided in those allergic to erythromycin or related antibiotics. An antidiarrheal drug such as loperamide (Imodium) or diphenoxylate (Lomotil) should be taken as needed to slow the frequency of stools, but not enough to stop the bowel movements completely. Diphenoxylate (Lomotil) and loperamide (Imodium) should not be given to children under age two.

Most cases of travelers' diarrhea are mild and do not require either antibiotics or antidiarrheal drugs. Adequate fluid intake is essential.

If diarrhea is severe or bloody, or if fever occurs with shaking chills, or if abdominal pain becomes marked, or if diarrhea persists for more than 72 hours, medical attention should be sought.

Though effective, antibiotics are not recommended prophylactically (i.e. to prevent diarrhea before it occurs) because of the risk of adverse effects, though this approach may be warranted in special situations, such as immunocompromised travelers.

Malaria in Peru: prophylaxis is recommended for all areas except Lima and its vicinity, the coastal areas south of Lima, the highland tourist areas (Cusco, Machu Picchu, and Lake Titicaca), and the departments of Arequipa, Moquegua, Puno, and Tacna. Most cases occur in Loreto where malaria transmission has reached epidemic levels. For a map showing the risk of malaria in different parts of the country, go to the Pan American Health Organization.

For more information, such as immunization, go to Travel Health.