Benadryl is a dumb drug. Why would anyone take too much? A double dose is nothing, ok? But it's like asking how much salt is deadly. I'm sure you can OD...
http://www.mentalhealth.com/drug/p30-b01.html#Head_4 And pediatric patients are more sensitive to all drugs, as are elderly patients. soooo...... Btw, I can't...