Preventing dehydration is a big concern since you really don't want to drink tap water or brush your teeth with it. Just remember to keep lots of bottled water around and remind everyone to stay well hydrated. A least in Mexico and Peru, every food store carried bottled water.

You might want to carry a dictionary and phrase book that covers Spanish medical terms. I had a toothache once in Peru so I needed antibiotics. The physician I found spoke no English so I had to describe my symptoms and what I needed in Spanish. A similar thing also happened to me in Mexico. I got good medical care both times but it would have been a problem if I hadn't been able to explain myself in Spanish.

Buen viaje,
Lynn