In my mother's case I would say it wasn't. It obviously is unpleasant being that way but she didn't have the illness the bug brings with it that makes you feel even worse.
I only gave you this as an example to say just because something may have a side effect even then it may not be a full throttle affair as it may read. Like I said earlier I took this antibiotic many times as a small child without any issues. Like Mouse mentioned it can just be some slight change in stool (antibiotics kill the good gut flora as well and that's why you can experience constipation, bowel changes, etc but they are easily resolved and even prevented) and eating yoghurt helps with this anyway.