When a significant amount of an anticholinergic is taken into the body, a toxic reaction known as acute anticholinergic syndrome may result. This may happen accidentally or intentionally as a consequence of recreational drug use. Anticholinergic drugs are usually considered the least enjoyable by experienced recreational drug users, possibly due to the lack of euphoria caused by them. In terms of recreational use, these drugs are commonly referred to as deliriants. Because most users do not enjoy the experience, they do not use it again, or do so very rarely. The risk of addiction is low in the anticholinergic class.
A common mnemonic for the main features of anticholinergic syndrome is the following:
Hot as a hare (hyperthermia)
Blind as a bat (dilated pupils)
Dry as a bone (dry skin)
Red as a beet (vasodilation)
Mad as a hatter (hallucinations/agitation)
The bowel and bladder lose their tone and the heart goes on alone (ileus, urinary retention, tachycardia)