urinary tract infection
"I used to have recurrent UTIs (up to 10 a year), and usually I took ciprofloxacin, which almost always gave me yeast infections and an upset stomach. This medication takes longer to cure the UTI, but it hasn't given me side effects. 
Beware of what everyone says about lung failure though :/ I'm taking a 100mg pill after sex nowadays, when I have more experience with it will share with you"