And the odds are you would have been fine with Imodium alone. And even then you hold off on the Imodium until you have symptoms. Ironically one of the common side effects of using Cipro is diarrhea.

It also has to be noted that Cipro does not speed acclimation to local bacterial flora and, in effect, you are reversing exposure and slowing natural acclimation. If you are exposed, get diarrhea, and take Cipro you may need to take more every time you are exposed. Avoid taking Cipro and stick to Imodium and your body will adjust over time and the local bacteria won't make you sick.

Of course the short-term visitor doesn't necessarily have that sort of time. The first course of action is to avoid the local flora by avoiding the water and contaminated foods. If you start to show symptoms take Imodium and treat the symptoms.

The use of antibiotics as a prophylactic, before infection, can backfire on you. Cipro doesn't differentiate between beneficial bacteria that serve and protect you and harmful bacteria. Killing off your friendly bacteria can leave you open to nasty varieties of bacteria, like clostridium difficile, to take root and cause long-term problems.