Cipro acts by hindering the production of certain proteins the bacteria needs to survive. Calcium-based products can dramatically interfere with the absorption of Cipro. Some pathogenic bacteria can become resistant to the drug which after all promotes their growth and division. Cipro should not be taken with or without food, however best absorption occurs when taken two hours after a meal and not when you are taking Cipro to make sure the drug doesn't accumulate in your kidneys.