How long will azithromycin stay in my system after the last dose?

Four days: Azithromycin has a long half life - which is both a blessing and a curse if you have side effects. The good news is, the medicine is quite well tolerated and is usually effective. If you are having side effects though, that could last for a little bit, because it won't clear out of your system right away. That's why the 'Z-pak' is only 5 days long - because it still works after the last pill.