In order to avoid the most usual stomach upset you have to be careful with the water you drink. It is not recommended to drink water directly from the tap. It is advisable to drink only bottled or boiled water. You have to be very cautious of where you eat. Making sure they adhere basic hygienic standards. If not it will be advisable to consume canned food.   When visiting cities in high regions, do not have carbonized drinks, eat fresh fruits and lemon flavor candies to avoid altitude sickness (soroche), also have tablets of "coramina" handy, these pills are ideal to avoid soroche.   You should also try to avoid heavy foods because digestion is much slower than in the coast.   A good idea would be to contact a medical insurance company, such as AIG Assist (242-9393), Assist Card (446-0710) or Pan American Assitance (446-4947) to be covered in case of an emergency. If you are not insured an need assistance contact the Tourist Protection Bureau (224-7888 in Lima and 0800-4-2579 from outside Lima), to receive information on the nearest medical center.