• Clinical science



Poisoning occurs when a substance that is inhaled, ingested, or absorbed through the skin has harmful or even deadly effects on normal body function. The type of poison, the amount taken, and the size and age of the individual involved are all factors in determining if a substance is actually harmful. In fact, many substances that are commonly thought of as harmless, including water and most vitamins, can be harmful if taken in excess. This learning card will focus on poisoning by several specific substances: organophosphates, cyanide, ethylene glycol and methanol, laundry and cleaning products, mushrooms and plants, and carbon monoxide and carbon dioxide. If poisoning is suspected, Poison Control (available 24/7 at 1-800-222-1222) should be contacted immediately to obtain information from poison specialists regarding management. If the poisonous substance is not known, the patient's case history together with clinical findings may help determine the causative agent, which is important for selection of a proper antidote (if available).

Poisoning due to overdose of pharmaceutical drugs is covered in learning cards dedicated to the specific drug, e.g., benzodiazepine overdose, anticholinergic poisoning, opioid intoxication, beta blocker poisoning. For intoxication with illegal drugs (e.g., cocaine, phencyclidine), see the learning card on substance use disorders.

Overview of antidotes

If further expert help is required: call Poison Control

  • Available 24/7 at 1-800-222-1222

Table of toxins and their specific antidotes/treatments

Drug/Toxin Toxicity Antidote/treatment and mechanism
Acetaminophen Hepatotoxicity → liver failure (see acetaminophen overdose) N-acetylcysteine: restores depleted hepatic glutathione
Amphetamines Indirect sympathomimetic effecthypertension, tachycardia, fever, cardiac arrest, and seizure Ammonium chloride: urine acidification
AChE inhibitors, organophosphates (parathion, E605) Cholinergic excess“DUMBBELSS” (see →Organophosphates) Atropine, pralidoxime (2-PAM): Reduction of parasympathetic effect

Antimuscarinic/anticholinergic agents

Anticholinergic excess → “Red as a beet, dry as a bone, hot as a hare, blind as a bat, mad as a hatter” (see anticholinergic syndrome)

Physostigmine : AChE inhibitor → elevated ACh levels

Barbiturates Efficacy of GABA CNS depression Sodium bicarbonate: urine alkalinization
Benzodiazepines Potency of GABA CNS depression Flumazenil: reversible, competitive antagonist
Beta blockers Bradycardia, hypotension, mental status changes, seizure, hypoglycemia, bronchospasm Glucagon : ↑ cardiac contractility
Carbon dioxide Tachycardia, cardiac arrhythmias, impaired consciousness, coma (see carbon dioxide) Oxygen and supportive care
Carbon monoxide Somnolence, agitation, cherry-red” skin tone, coma (see carbon monoxide) 100% oxygen, hyperbaric oxygen

Confusion, seizures, coma, cardiac arrhythmias, respiratory failure (see cyanide poisoning)

  • Cyanide-binding agent (hydroxycobalamin)
  • Methemoglobin-forming agent
  • Sulfur donor (sodium thiosulfate)
Digitalis Changes in vision , nausea, vomiting, cardiac arrhythmias Anti-digitalis Fab
Methanol, ethylene glycol (antifreeze)

Altered mental status, seizures, dyspnea, anion gap metabolic acidosis (see ethylene glycol poisoning and methanol poisoning)

Fomepizole, ethanol

Heparin Bleeding Protamine sulfate: complex formation with heparin
Metals Findings depend on specific metal poisoning Arsenic, mercury, gold: dimercaprol, succimerchelation
Copper, arsenic, gold: penicillamine chelation
Iron: deferoxamine (“De-Fe-roximine”) → chelation
Lead: EDTA, succimer, dimercaprolchelation
Methemoglobin Cyanosis, respiratory depression, coma, seizures Methylene blue, vitamin C

Altered mental status, respiratory depression, pupillary miosis

Naloxone, naltrexone: opioid antagonists
Salicylates Tinnitus, vertigo, nausea, diarrhea, hyperventilation, arrhythmia Sodium bicarbonate , dialysis, activated charcoal
Streptokinase, urokinase, recombinant tPA Bleeding Aminocaproic acid: plasmin inhibition
Tricyclic antidepressants 3 Cs: convulsions, coma, cardiotoxicity (long QT); anticholinergic side effects

Sodium bicarbonate (plasma alkalization ) for cardiac toxicity

Benzodiazepines for seizures

Warfarin Bleeding Vitamin K (delayed antidote), FFP (immediate antidote)

Activated charcoal is ineffective in the treatment of heavy metal toxicity (e.g., mercury, lead), lithium, acids, bases, and toxic alcohols such as methanol.



Always mind your own safety (neoprene gloves, gown, and charcoal cartridge mask), remove contaminated clothes, and wash contaminated skin!

The greatest danger in organophosphate poisoning is respiratory failure!

DUMBBELSS for the clinical features of organophosphate poisoning = Diarrhea, Urination, Miosis, Bronchospasm and Bradycardia, Neuromuscular Excitation, Lacrimation, Sweating and Salivation!



Consider cyanide poisoning in a patient with chronic renal failure who has very recently undergone treatment for a hypertensive emergency and is now presenting with altered mental status and lactic acidosis!


Ethylene glycol, methanol and isopropyl alcohol

Ethylene glycol

  • Brief description: : alcohol primarily used in radiators to raise the boiling point and lower the freezing point; sweet taste
  • Sources of exposure
    • Ingested as ethanol substitute by alcoholics
    • Self-harm attempts
    • Accidental ingestion
  • Clinical features


  • Sources of exposure
    • Fuels (highly flammable)
    • Ingested as ethanol substitute by alcoholics
    • Self-harm attempts
    • Accidental ingestion
    • Improper distillation of spirits
  • Effects
  • Clinical features
    • Nausea, abdominal cramps
    • Headache, altered mental status
    • Severe acidosis
    • Optic neuropathy associated with vision problems and blindness

Isopropyl alcohol

  • Sources of exposure
  • Effects: isopropyl alcohol is metabolized to acetone → ↑ serum ketones
  • Clinical features
    • Altered mental status, coma
    • Nausea, vomiting, abdominal cramps
    • Fruity mouth odor
    • Massive ingestion: features of shock

Management of ethylene glycol, methanol, and isopropyl alcohol poisoning

Always consider simultaneous intoxication with more than one substance and adjust the management plan accordingly!


Laundry and cleaning products


  • Brief description: chemicals used as shampoo, all-purpose cleaners
  • Clinical features
  • Management
    • Secure airways, oxygenation, monitoring, fluid resuscitation
    • Endoscopy to evaluate severity of injury
    • Perform ABG to evaluate for pH
    • Anti-foaming agent: polydimethylsiloxane (dimethicone)

Caustic liquids

Do not induce vomiting, as this may cause further damage to the esophagus! Do not attempt to neutralize the alkali with a weak acid, as this may lead to vomiting or local heat production!


Mushrooms and plants

Amanita phalloides (death cap mushroom)

Atropa belladonna (belladonna, deadly nightshade)

Anticholinergic syndrome: "Blind as a bat, mad as a hatter, red as a beet, hot as hell, dry as a bone, the bowel and bladder lose their tone, and the heart runs alone.”


Carbon monoxide and carbon dioxide

Carbon monoxide (CO)

History is very important for diagnosis! Suspect carbon monoxide poisoning when multiple people from the same confined household complain of the headache and fatigue.

Since standard pulse oximetry cannot distinguish between COHb and oxyhemoglobin, it will show incorrectly high oxygen saturation levels!

Carbon dioxide (CO2)

  • Properties: colorless, odorless gas
  • Exposure: : increased production during fermentation processes, e.g., in grain silos, wells, cesspools
  • Clinical features
    • In atmospheric concentrations under 0.3%: no health risks
    • In atmospheric concentrations of 5%–8%: headaches, vertigo, dyspnea and tachypnea, tachycardia and arrhythmias, impaired consciousness
    • In atmospheric concentrations > 8%: tremors, sweating, diminished hearing, loss of consciousness, respiratory depression, respiratory arrest
  • Management
    • Removal of patient from source of carbon dioxide
    • Oxygen and supportive care


Ancillary substances

Ingestion of cigarettes (nicotine)

  • Clinical features
    • Vomiting, pallor, tachycardia, perspiration
    • Following ingestion of large amounts: (↓ blood pressure, heart rate), respiratory failure)
  • Treatment: activated charcoal up to 60 minutes after ingestion

Ingestion of a button battery

  • Clinical features
    • Possibly asymptomatic
    • Airway obstruction, coughing
    • Drooling, vomiting
    • Chest discomfort, dysphagia
  • Management: based on patient age, size of battery, and suspected location of battery
    • X-ray to determine location and confirm diagnosis
    • Immediate endoscopic removal indicated if:
      • Battery is located in the esophagus
      • Battery is located in the stomach or lower in the digestive tract and a magnet was co-ingested

Always consider the possibility that a button battery has been ingested if the parents think that their child has ingested a “coin” or another foreign object.