Anticholinergic Toxicity Clinical Presentation

Updated: Jul 28, 2016
  • Author: Mityanand Ramnarine, MD, FACEP; Chief Editor: Asim Tarabar, MD  more...
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For all patients with suspected poisoning, determine the precise substance(s) ingested, time of ingestion, quantity ingested, rationale for ingestion, and co-ingestants. Ascertain patient compliance, medical history, prescription medications, and nonprescription medications (including natural or herbal products).

Many medications have anticholinergic properties, which can result in additive toxicity. Always inquire about use of dermally applied drugs (ie, scopolamine transdermal delivery system).

In a study that included 30 patients with chronic pain and 30 control patients, the pain patients were at higher cognitive risk from anticholinergic burden, especially those aged 30 to 39 years. The average number of medications used by patients in the chronic pain group was 3.93, compared with 1.20 in the control group. None of the patients were taking opioid analgesics. The medications used by patients in this age group were more likely to have anticholinergic properties than those used by older patients. [5]

In older adults, long-term use of anticholinergic drugs has been linked to cognitive impairment. A study in patients aged 65 years and older found that the risk for cognitive impairment was increased by 50% in those who had taken three or more mild anticholinergic drugs for more than 90 days and by 100% in those taking one or more strong anticholinergics for more than 60 days. [6, 7]



Anticholinergic syndrome results from the inhibition of muscarinic cholinergic neurotransmission. Clinical manifestations are caused by CNS effects, peripheral nervous system effects, or both.

Remember common signs and symptoms with the mnemonic, "red as a beet, dry as a bone, blind as a bat, mad as a hatter, hot as a hare, and full as a flask." The mnemonic refers to the symptoms of flushing, dry skin and mucous membranes, mydriasis with loss of accommodation, altered mental status (AMS), fever, and urinary retention, respectively.

Additional manifestations include the following:

  • Sinus tachycardia
  • Decreased bowel sounds
  • Functional ileus
  • Urinary retention
  • Hypertension
  • Tremulousness
  • Myoclonic jerking

Patients with central anticholinergic syndrome may present with the following:

  • Ataxia
  • Disorientation
  • Short-term memory loss
  • Confusion
  • Hallucinations (visual, auditory)
  • Psychosis
  • Agitated delirium
  • Seizures (rare)
  • Coma
  • Respiratory failure
  • Cardiovascular collapse


In addition to anticholinergics, drug classes that have anticholinergic properties include antihistamines, antipsychotics, antispasmodics, cyclic antidepressants, and mydriatics. Furthermore, several varieties of plants contain anticholinergic substances.

Anticholinergics include the following:

  • Atropine, scopolamine
  • Glycopyrrolate
  • Benztropine, trihexyphenidyl

Antihistamines with anticholinergic properties include the following:

  • Chlorpheniramine
  • Cyproheptadine
  • Doxylamine
  • Hydroxyzine
  • Dimenhydrinate
  • Diphenhydramine
  • Meclizine
  • Promethazine

Antipsychotics with anticholinergic properties include the following:

  • Chlorpromazine
  • Clozapine
  • Mesoridazine
  • Olanzapine
  • Quetiapine
  • Thioridazine

Antispasmodics with anticholinergic properties include the following:

  • Clidinium
  • Dicyclomine
  • Hyoscyamine
  • Oxybutynin
  • Propantheline

Cyclic antidepressants with anticholinergic properties include the following:

  • Amitriptyline
  • Amoxapine
  • Clomipramine
  • Desipramine
  • Doxepin
  • Imipramine
  • Nortriptyline
  • Protriptyline

Mydriatics with anticholinergic properties include the following:

  • Cyclopentolate
  • Homatropine
  • Tropicamide

Miscellaneous drugs with anticholinergic properties include the following:

  • Carbamazepine
  • Cyclobenzaprine
  • Orphenadrine

Plants with anticholinergic properties include the following:

  • Amanita muscaria (fly agaric)
  • Amanita pantherina (panther mushroom)
  • Arctium lappa (burdock root)
  • Atropa belladonna (deadly nightshade)
  • Cestrum nocturnum (night-blooming jessamine)
  • Datura suaveolens (angel's trumpet)
  • Datura stramonium (jimson weed)
  • Hyoscyamus niger (black henbane)
  • Lantana camara (red sage)
  • Solanum carolinensis (wild tomato)
  • Solanum dulcamara (bittersweet)
  • Solanum pseudocapsicum (Jerusalem cherry)
  • Solanum tuberosum (potato)