Personally, I never had the whole trepedation thing about the shots. Beofre my son went, I would give him one dose of tylenol and then he would get the shots. We never had any troubles - no fussiness, no irritability or anything. I really believe it was the preemptive tylenol and more likely, my calmness about it. (Yes I know there are some that get real reactions and I am not negating this, however I think much of a babies reactions are due to picking up on the mother's worries)