how long does it take azithromycin to work for sinus infection?
For this reason, a course of azithromycin should be completed in 3 days or less for sinusitis (as in a Zithromax Tri-Pak), and should not be spread out over 5 days (as in a Zithromax Z-Pak). Azithromycin induces antibiotic resistance to itself quickly if prescribed in doses that are too low to kill the bacteria.