Introduction to Toxidromes

Toxidromes (portmanteau of toxic + syndrome) are a medical syndrome caused by a elevated levels of a substance in the body, and often secondary to a drug overdose or adverse drug reaction.

Toxidromes on Physical Exam

HR/BP RR Temperature Pupils Bowel Sounds Diaphoresis
Anticholinergic N
Cholinergic N or N N
Extrapyramidal Symptoms N or N or N N N N or
Sedative-Hypnotic N
Serotonin Syndrome
Neuroleptic Malignant Syndrome N N or

Toxidromes Signs and Symptoms Comparison

Adapted from: Toronto Notes 2017. University of Toronto Press, 2017.
Toxidrome Overdose Signs and Symptoms Examples
Anticholinergic • ”Blind as a bat” (blurred vision, dilated pupils)
• “Dry as a bone” (dry mouth and skin)
• “Red as a beet” (vasodilation/flushing)
• “Mad as a hatter” (confusion, cognitive impairment, delirium, agitation, hallucinations, tremors, ataxia)
• “Hot as a hare” (hyperthermia)
• “And the heart runs alone” (tachycardia)
• Antidepressants (e.g. TCAs)
• Cyclobenzaprine (Flexeril®)
• Carbamazepine
• Antihistamines (e.g. diphenhydramine)
• Antiparkinsonians
• Antipsychotics
• Antispasmodics
• Belladonna alkaloids (e.g. atropine)
Cholinergic S - Salivation
L - Lacrimation
U - Urination
D - Diaphoresis
G - GI Upset
E - Emesis
• Bradycardia and pin-point pupils can result as well!
• Natural plants: mushrooms, trumpet flower
• Anticholinesterases: physostigmine
• Insecticides (organophosphates, carbamates)
• Nerve gases
Extrapyramidal • Dysphonia, dysphagia
• Rigidity and tremor
• Motor restlessness, crawling sensation (akathisia)
• Constant movements (dyskinesia)
• Dystonia (muscle spasms, laryngospasm, trismus, oculogyric crisis, torticollis)
• Major tranquilizers
• Antipsychotics
Hemoglobin Derangements • Increased respiratory rate
• Decreased LOC
• Seizures
• Cyanosis unresponsive to O2
• Lactic acidosis
• CO poisoning (carboxyhemoglobin)
• Drug ingestion (methemoglobin, sulfmethemoglobin)
Opioid • Hypothermia
• Hypotension
• Respiratory depression
• Dilated or constricted pupils (pinpoint in opioid)
• CNS depression
• Opioids (morphine, heroin, fentanyl, etc.)
Sedative/ Hypnotic, Alcohol • Drowsiness
• Slurred speech
• Nystagmus
• Hypotension
• Ataxia
• Coma
• Respiratory depression
• Cardiorespiratory arrest
• Alcohol
• Benzodiazepines
• Barbiturates
• Gamma hydroxybutyrate (GHB)
Sympathomimetic • Increased temperature
• CNS excitation (including seizures)
• Tachycardia, HTN
• N/V
• Diaphoresis
• Dilated pupils
• Amphetamines, caffeine, cocaine, LSD, phencyclidine
• Ephedrine and other decongestants
• Thyroid hormone
• Sedative or EtOH withdrawal
Serotonin Syndrome • Mental status changes
• Dilated pupils
• Autonomic hyperactivity
• Hyperreflexia
• Clonus
• Hyperthermia
• Diarrhea
MAOI, TCA, SSRI, opiate analgesics
Cough medicine, weight reduction medications
Neuroleptic Malignant Syndrome • Diaphoresis
• Hyperthermia
• CK elevation
• Autonomic hyperactivity (hypertension, HR/RR increase)
• “Lead-pipe” rigidity
• Bradyreflexia
Dopamine antagonists