There are a few classic features in anticholinergic syndrome. The offending medications block acetylcholine at both central and peripheral synapses and inhibit parasympathetic nervous system function, resulting in a variety of symptoms / signs. 

  • Mad as a hatter (Altered mental status)
  • Blind as a bat (mydriasis/dilated pupils)
  • Hot as a hare (or hell or Hades)
  • Red as a beet
  • Dry as a bone

Anticholinergic effects can be useful – atropine used to counter the sialogogue effects of ketamine

Patients with an anticholinergic toxidrome may present with some or all of these findings. Possible toxins with anticholinergic properties include the following:

  • Tricyclic Antidepressants (TCA) – imipramine, amitriptyline, nortriptyline (readily available over the internet now unfortunately)
  • Antihistamines- fexofenadine, diphenhydramine, dimenhydrinate, loratadine, chlorpheniramine
  • Overactive bladder medication – oxybutynin, tolterodine, trospium

Treatment:  is mostly supportive. Please see specific therapies for TCA ingestions. Also keep in mind that anticholinergic medications can be used recreationally as drugs of abuse and may present as non self-harm induced ingestions.