Quote Originally Posted by DrivenMind
Benedryl is one of the most powerful, and potentially dangerous types of hallucinogenic drugs in the world, and belonging to a subclass of dissociative drugs called "Deliriants", which also includes nutmeg. They differ from classic hallucinogens in that they cause delirium, and user cannot readily identify a hallucination from reality.
nah its not a hallucinogen at all, its a anti-histamine, with delirium as side effect when overdosed.

Scopolamine and atropine, anticholinergic deleriant, also anti histamines are thousands of times more powerful than Diphenhydramine. They are found in a plant called Datura, which is a relative of Belladona and Deadly nightshade, which also containe high amounts of Scopolamine and Atropine.

http://www.erowid.org/plants/datura/datura_basics.shtml