Differential Diagnosis of Anticholinergic Toxidrome

There are a number of frequently taken drugs that commonly cause the anticholinergic syndrome.

The most common (in Australia) are:

• Antihistamines
• Anticholinergic drugs including
  • atropine
  • benztropine
  • benzhexol (trihexyphenidyl)
  • procyclidine
  • orphenadrine
• Tricyclic antidepressants (TCAs)
• Neuroleptics (in particular thioridazine and chlorpromazine)
• Carbamazepine
• Anticholinergic plants
  • Datura (Brugmansia) stramonium (Angel's trumpet)
  • Atropa belladonna (Deadly Nightshade)

Features that help to differentiate between these drugs are:

• LEVEL OF CONSCIOUSNESS
• PUPIL SIZE and REACTION
• MYOCLONIC JERKING, SEIZURES or HYPERREFLEXIA
• NYSTAGMUS
• HEART RATE
• BOWEL SOUNDS
• ECG CHANGES
• RESPONSE TO ANTAGONISTS
• BLOOD CONCENTRATIONS