What is the treatment for zithromax overdose?

No antidote for it: I have never seen or heard of any serious trouble with zithromax od--from people have accidentally taken 3-4 times what is recommended. Single dose of 2gm (4x more than usual dose of longer course of 5 days) is often given these days, and those who have trouble usually end up vomitting it out. So, od will likely result in vomitting/diarrhea etc.. If you have trouble, consult doc. Good luck.