it has to do with the extent of the bad trip. there are standable bad trips and others that feel like hell. but as with other situations, its good to have an escape route. and swim would definately reccomend not considering that escape route unless you are truly in danger. not pyschological stuff but real physical dilemmas. for example, if you're blood pressure is way too high or you're on the verg of a heart attack, one should take easiest way out. and yes, most of the time these scenarios are not likely, but its best not to rule them out especially when trying something new.. but in these extreme cases its not simply a preference to end a trip but a neccesity; your life may depend on it. Otherwise, its probably better for your overall pysche to deal with a bad trip if its not life threatening. try your best to intergrate it.
as for anti-histamines.. from what SWIM gathers they are (perhaps were) used to end pyschotic episodes, not even sure if they would be applicable to chemical-induced experiences... perhaps to an extent. don't know anything about dose but its probably higher than say for allergies. although dangerous in itself theres a definite logic and theory to this application, swim has heard it before but doesn't remember it now.
