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GuidelinesEML (Adult Hospital STG)

Poisoning

Description Diagnostic criteria General measures Referral DESCRIPTION Frequently encountered poisonings in adults are due to: analgesics anti-infectives ethanol/alcohol hydrocarbons e.g. paraffin anticonvulsants antihistamines irritants and corrosives pesticides cardiodepressants iron sedatives, antidepressants & antipsychotics toxic alcohols e.g. methanol, ethylene glycol Maintain a high ind

Description

Diagnostic criteria

General measures

Referral

DESCRIPTION

Frequently encountered poisonings in adults are due to:

  • analgesics
  • anti-infectives
  • ethanol/alcohol
  • hydrocarbons e.g. paraffin
  • anticonvulsants
  • antihistamines
  • irritants and corrosives
  • pesticides
  • cardiodepressants
  • iron
  • sedatives, antidepressants & antipsychotics
  • toxic alcohols e.g. methanol, ethylene glycol

Maintain a high index of suspicion for intentional ingestion in adults presenting with poisoning.

DIAGNOSTIC CRITERIA

Clinical

Clinical presentations due to poisoning can be divided into ‘toxidromes”:

Anticholinergic: e.g. antihistamines, amanita pantherina/muscaria, atropine

  • fever
  • dry skin and mouth
  • ileus
  • blurred vision
  • flushing
  • mydriasis (dilated pupils)
  • tachycardia
  • coma
  • urinary retention
  • hallucinations and seizures

Cholinergic: e.g. organophosphates

  • salivation
  • diarrhoea
  • lacrimation
  • vomiting
  • urination
  • bronchorrhoea
  • miosis (pinpoint pupils)
  • bradycardia

Dystonic: e.g. haloperidol

  • torticollis
  • opisthotonos
  • intermittent spasms and tongue thrusting

Opiates: e.g. morphine

  • miosis (pinpoint pupils)
  • decreased bowel sounds
  • respiratory depression
  • hypothermia
  • bradycardia
  • hypotension
  • altered (decreased) consciousness

Salicylism: e.g. aspirin

  • tachypnoea
  • agitation
  • seizures
  • coma
  • metabolic acidosis and respiratory alkalosis

Sedative-hypnotic: e.g. alcohol, benzodiazepines

  • obtundation or coma

Sympathomimetic: e.g. cocaine, amphetamines

  • hypertension
  • agitation
  • tachycardia
  • sweating
  • hyperthermia
  • dilated pupils

Sympathomimetic toxidrome partially resembles anticholinergic toxidrome, i.e. fight, flight and fright response, however the sympathomimetic toxic patient is sweaty as opposed to hot dry skin seen with anticholinergic toxicity.

Toxic alcohols: e.g. ethylene glycol, methanol

  • metabolic acidosis
  • nausea and vomiting
  • increased osmolar and anion gaps
  • tachycardia and arrhythmias
  • visual disturbances (methanol)
  • renal failure (ethylene glycol)
  • inebriation and depressed level of consciousness
  •  hyperventilation

GENERAL MEASURES

It is very important to ascertain if a potentially TOXIC DOSE has been taken BEFORE instituting any potentially harmful decontamination procedures in an asymptomatic patient.

  • Take a complete and accurate history, ascertain all relevant facts, and do a complete clinical examination.
  • Maintain a high index of suspicion.
  • Obtain a collateral history, especially for patients with impaired consciousness. A special effort should be made to obtain tablets, packets, containers, etc. to identify agents involved.
  • Stabilise the patient and monitor basic clinical parameters, i.e.:
    • blood pressure and heart rate
    • hydration
    • airway and ventilation
    • neurological status
    • temperature
    • glucose
  • Persistent or prolonged seizures may require medical management. Phenytoin should not be used in cases of poisoning due to substances known to be cardiotoxic e.g. tricyclic antidepressants, or where there is evidence of clinical cardiotoxicity.
  • Prevent physical injury in the restless – avoid excessive sedation.
  • Limit toxicological investigations to those that may influence/alter management. It is important to note the time after ingestion when blood was taken in order to correctly interpret results (e.g. paracetamol and iron levels).

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Decontamination

Limit further exposure to poison for the patient and protect healthcare workers where necessary.

Topical exposure

In the case of skin exposure, remove clothes and wash the body. Showering may be useful.
Remove eye contaminants, especially alkalis, acids and other irritants, by continuous irrigation of the eye with sterile water or normal saline for 15–20 minutes. Analgesic eye drops may be required to perform this adequately.

Gut decontamination
Methods of gut decontamination include:

  • Gastric lavage
  • Activated charcoal administration
  • Whole bowel irrigation

Gastric lavage

  • If deemed beneficial, it should only be performed by experienced staff and
  • within 60 minutes of ingestion.
  • Can be considered for cases with:
    • potentially life-threatening ingestions AND
    • a protected airway i.e. fully awake and cooperative or intubated with a depressed level of consciousness.
  • Gastric lavage is contra-indicated after ingestion of corrosive substances and volatile hydrocarbons such as paraffin.
  • Technique:
    • Place patient in left lateral head down position.
    • Insert orogastric tube if possible, with largest bore and rounded tip.
    • Insert 200mL warmed water or normal saline, and aspirate.
    • Continue until recovered solution is clear of particulate matter.

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Activated charcoal

May reduce systemic absorption of a variety of poisonous substances. The greatest benefit is achieved if activated charcoal is given within one hour after ingestion; however, where gastric emptying is delayed by certain substances, there may be a longer period of time in which it is effective. Activated charcoal must only be given in cases where the airway is protected; i.e. fully awake and cooperative patient or intubated with a depressed level of consciousness.

LoE:IVbxx 

Activated charcoal may be useful if these poisons are taken in toxic dose Poisons where charcoal is ineffective and should not be given
- carbamazepine, barbiturates, phenytoin

- dapsone, quinine

- theophylline

- salicylates

- mushroom poisoning (Amanita phalloides)

- slow-release preparations

- digoxin

- beta-blockers

- NSAIDs		 - ethanol, methanol, ethylene glycol

- brake fluid

- petroleum products (e.g. petrol or paraffin)

- iron salts

- lead, mercury, arsenic

- lithium

- strong acids or alkalis

- other corrosive agents (e.g. household detergents)

Table 19.2: Appropriate use of activated charcoal

  • Activated charcoal, oral, 50 g (equivalent to 36 level medicine measures) diluted in 100 mL water.
    • When mixing, add a small amount of water to charcoal in a container.
    • Cap and shake container to make a slurry and then dilute further.
    • Repeated doses of activated charcoal (i.e. 50 g every 4 hours) are effective in enhancing elimination of substances that undergo enterohepatic circulation, e.g. carbamazepine, dapsone, phenobarbitone, quinine or theophylline.

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Whole bowel irrigation

Whole bowel irrigation can be done for potentially toxic ingestions of substances that are:

  • not absorbed by activated charcoal (e.g. iron and lithium)
  • modified-release and enteric-coated products
  • or for removal of illicit drugs in body packer

Patients must have a protected airway i.e. fully awake and cooperative or intubated with a depressed level of consciousness.

  • Polyethylene glycol (PEG) balanced electrolyte solution, NGT, 1500-2000 mL/hour.
    • Continue until rectal effluent is clear.

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Other treatment modalities

Sodium bicarbonate alkalinisation

Urine alkalinisation enhances renal elimination of certain toxins (salicylates) and serum alkalinisation improves acidosis enhancing myocardial functioning (TCAs) and reducing neurotoxicity (salicylates).

This is achieved by administering intravenous sodium bicarbonate (NaHCO3) to maintain a urinary pH 7.5-8.5 or serum pH 7.45-7.55.

 CAUTION
This is a high-risk procedure and should only be performed in consultation with a specialist.

Haemodialysis

Patients with symptomatically severe poisoning substances including salicylates, lithium, ethylene glycol, methanol, ethanol, and theophylline, may benefit from dialysis (http://www.extrip-workgroup.org/).
Refer patient to a hospital with dialysis facilities.

Antidotes

There are a limited number of antidotes for poisoning by certain substances, e.g. N-acetylcysteine for paracetamol, naloxone for opioids. Each antidote has specific criteria and indications for use.

Once medically stable: Assess and manage intentional poisoning – self-harm or harm by others:

  • Take a history of circumstances around the poisoning, substance use and mental illness, and examine the mental state.
  • Assess further suicide risk – see: Suicide risk assessment.
  • Refer to social, psychological and/or psychiatric services.

Assess and manage a substance use disorder:

  • Quantify the amount of substance used and related harms with these rating scales and discuss findings with the patient:
    • ASSIST: http://www.who.int/substance_abuse/activities/assist/en/
    • DUDIT: https://www.emcdda.europa.eu/system/files/attachments/12173/DU DIT-English-version.pdf
    • Provide brief intervention with motivational interview.
    • Refer for rehabilitation.

REFERRAL

  • Severely ill patient for ventilatory/circulatory support.
  • Relevant diagnostic testing not available, e.g. paracetamol levels, acid/base assessment.
  • Relevant medication/antidote not available.
  • Dialysis/haemoperfusion required.

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Standard Treatment Guidelines and Essential Medicines List for South Africa, Adult Hospital Level, 2020-2024_Version 2.0_27 March 2025

Chapter 19 Poisoning_Poisoning

Drugs mentioned

NeoHealth® ID 17442 · updated 7/9/2025