Prior to the infamous lawsuit, coffee cups at McDonald's did not warn that the coffee is hot; does the fact that this warning was not on the coffee cups mean that the coffee is cold?
And because a package doesn't list every conceivable side effect does not mean that it can't happen. Many people have a very cavalier attitude regarding over the counter (OTC)medications. I have seen patients end up on kidney dialysis because they took too much ibuprofen for their back pain. There is a REASON that drug packaging has warnings. Benadryl packaging clearly warns "CHILDREN UNDER 6 YEARS OF AGE CONSULT A DOCTOR". After seeing this story, people will now know why this warning is there.
BTW, it is OK for an infant to use Benadryl in certain situations IF PRESCRIBED BY A DOCTOR.