MICA · FIRST-LINE LEARNING NOTES
Understand, prioritise and organise follow-up
In possible poisoning, protect responders, support vital functions and identify the exposure before pursuing an antidote.
Ensure safety and recognise severity
Impaired consciousness, slow or difficult breathing, seizure, collapse or severe agitation require emergency medical help. Avoid exposure to a dangerous atmosphere or chemical; extraction from a contaminated area requires appropriately equipped rescuers when safety is uncertain. Headache, nausea or malaise affecting several people in the same room suggests carbon monoxide. A conventional pulse oximeter may then provide misleading reassurance.
[1][2]Obtain an actionable exposure history
Identify substance, concentration, possible amount, route, timing and repeated exposures; retain packaging or photographs without unnecessary handling. Ask about co-ingestion, alcohol, medicines, possible pregnancy and intentional or accidental exposure. Record vital signs, pupils, neurological state and glucose; select ECG and laboratory tests according to the substance and presentation. Contact a poison centre or toxicology specialist early to define testing, delayed risk and monitoring.
[1][2][3]A reassuring initial examination does not exclude delayed toxicity, particularly with modified-release products or uncertain quantities. Carbon monoxide exposure may affect several people in one location; standard pulse oximetry cannot exclude poisoning. Clarify exposures with relatives when the history is incomplete, and do not leave an unstable patient alone.
[1][2]Avoid actions that worsen harm
Do not induce vomiting, attempt household neutralisation or give food or drink without appropriate advice. Activated charcoal, lavage, antidotes and extracorporeal elimination are never universal reflexes. In suspected opioid overdose, ventilation and emergency assistance remain priorities; naloxone may be required according to local protocols and available training. Improvement after an antidote does not remove the need for observation.
[1][3]- Prevent further exposure without endangering rescuers and activate appropriate emergency services.
- Do not induce vomiting or give gastrointestinal decontamination without toxicological guidance.
- Agree the location and duration of observation with an expert; rapid improvement alone does not justify discharge.
Anticipate delayed toxicity and recurrence
Initially absent symptoms do not establish safety. Observation duration and repeat tests depend on the substance, formulation, co-ingestions and reliability of the history. After carbon monoxide exposure, explain the possibility of delayed neurological symptoms and arrange indicated follow-up. Intentional poisoning also requires assessment of psychological safety and an appropriate care pathway before discharge, alongside somatic recovery.
[1][2][3][4]A learning situation
FICTIONAL CASE · SELF-REFLECTION WITHOUT A SCORE
Two people in the same home develop headache and nausea while a heater is operating. One is drowsy. A fingertip pulse oximeter displays an apparently normal saturation.
Which approach takes priority?
Read the reasoning
Suspect shared carbon monoxide exposure, alert emergency services and prevent further exposure. Normal conventional pulse oximetry does not exclude poisoning. Urgent assessment uses exposure history, examination and appropriate carboxyhaemoglobin measurement without delaying indicated treatment. Drowsiness signals severity, and other occupants also require assessment.
References and scope
- Poisoning — emergency advice, assessment and observation (reviewed June 2025) ↗
- Clinical Guidance for Carbon Monoxide Poisoning Following Disasters and Severe Weather (reviewed August 2026) ↗
- Opioid overdose — fact sheet, 29 August 2025 ↗
- Self-harm: assessment, management and preventing recurrence — NG225: Recommendations ↗
Original educational synthesis for adult first-line practice. International references must be interpreted with the clinical setting and local care pathways. Independent human scientific review remains to be confirmed.