Ciprofloxacin must not be used in cases of hypersensitivity to ciprofloxacin or other quinolone chemotherapeutics or any of the excipients. Concurrent administration of ciprofloxacin and tizanidine is contraindicated since an undesirable increase in the serum tizanidine concentrations associated with clinically relevant tizanidine-induced side effects (hypotension, somnolence, and drowsiness) can occur.