Ciprofloxacin is an antibiotic. It belongs to a group of antibiotics called fluoroquinolones. It is used to treat different types of bacterial infections such as bone and joint infections, respiratory or sinus infections, skin infections, urinary tract infections, and certain types of diarrhea. It can also be used to treat gonorrhea. Ciprofloxacin is also used to treat people who have been exposed to anthrax or certain types of plague. Side effects include diarrhea, dizziness, headache, upset stomach, abdominal pain, rash, nausea, or trouble sleeping. If these effects persist or worsen, tell your doctor or pharmacist immediately. This medication passes into breast milk