I have taken two doses of Zithromax already for bronchitis. I took 2 in the ER and one last night. I woke up this morning feeling amazingly better. So far I've had no side effects. I've had a little bit of cramping but I am going to blame that on being on my period, and its not even that bad. I was so scared hearing all of these horror stories. I already have anxiety and a racing heart at times, but this honestly has not made me nervous or anything. I'm just happy it will help my infection and it's already helping so fast!