As far as I knew, a peanut allergy i usually a fatal one. I saw something about it a few years ago and seem to remember it saying that some allergies tend to be either fatal or non-existant with no real grey area of severity. So, if I am remembering this correctly, it seems that an inhaler really wouldn't help for someone who swallowed a peanut. Of course, I could easliy be wrong about this.
Gabriel