Overview of risk assessment for poisonings

Risk assessment involves gathering information about the patient and the exposure, and is the most important step in managing poisonings after initial resuscitation of the patient. In most cases, risk assessment reassures the clinician that supportive care is sufficient, preventing the use of unnecessary interventions; however, it can alert the clinician to potentially severe toxicity and direct acute management, and will inform appropriate patient disposition.

Risk assessment requires as much history about the exposure as possible from the patient and others (eg relatives, paramedics). If this is not available, management needs to be based on the worst-case scenario—consider seeking advice from a clinical toxicologist or poisons information centre—telephone 13 11 26.

Deliberate self-poisoning has a higher risk of toxicity than unintentional or accidental poisonings. Most patients presenting with deliberate self-poisoning have taken more than one substance. Risk assessment and management is required for each substance. Alcohol is commonly co-ingested, but a high serum ethanol concentration does not exclude co-ingestion of other substances.

Risk assessment for poisonings includes consideration of:

  • patient details—age, weight or size, sex, medical history, medication history (including regular medication that may cause tolerance or interactions)
  • the suspected drug or toxin involved, including
    • intrinsic toxicity
    • route of exposure (eg ingestion, dermal contact, inhalation, injection, bite, sting)
    • toxic dose—toxic doses of drugs can cause additional and different effects to those seen at therapeutic doses. Do not extrapolate toxic effects of drugs from their known effects at therapeutic doses. Toxic doses of drugs and toxins are included in the individual drug and toxin monographs if there is evidence to support them
    • nature of exposure—acute poisoning versus chronic ingestion/accumulation (particularly relevant for digoxin, lithium and paracetamol poisonings)
    • possible co-ingestants
  • intent of the poisoning—accidental or unintentional poisoning, deliberate self-poisoning or nonaccidental injury
  • time since exposure
  • clinical effects—presenting symptoms and signs, features of specific toxidromes (toxic syndromes)
  • results from investigations already done—see Key investigations for poisonings.