Does cipro (ciprofloxacin) treat sinus infections if levaquin fails to help?

Depends & not always: Cipro (ciprofloxacin) and Levaquin are both "fluoroquinolone" antibiotics. Cipro (ciprofloxacin) will only work better if the bacteria is resistant to Levaquin and sensitive to Cipro (ciprofloxacin). However, most of the time, it is a good idea to use a different "class" of antibiotic all together if one fails. Also, antibiotic treatments can also fail because the sinusitis is actually viral, allergy, and inflammatory (such as polyps).