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Poisoning & Overdose

Support the airway, find the toxidrome, call the antidote.

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Your objective: explain the approach, recognize important warning signs, then test your recall.

Abbreviations explained
ACS
Acute coronary syndrome
OMI
Occlusion myocardial infarction
ECG
Electrocardiogram
PE
Pulmonary embolism
POCUS
Point-of-care ultrasound
QTc
QT interval corrected for heart rate
LBBB
Left bundle branch block
RBBB
Right bundle branch block
hs-cTn
High-sensitivity cardiac troponin
CTA
Computed tomography angiography
ICU
Intensive care unit
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The jobSupport the airway, find the toxidrome, call the antidote.

  1. ABCDE first; never delay glucose.
  2. Name the toxidrome: vitals, pupils, skin, bowel, temperature.
  3. Paracetamol and salicylate in every deliberate overdose; NAC on timing and probability, not symptoms.
  4. Call the poison centre early for mixed, delayed-release, or unknown ingestions.

The poisoned patient is treated by pattern: ABCDE first, then toxidrome recognition (vitals, pupils, skin, mental status), focused antidotes, and decontamination when appropriate.

Paracetamol deserves special respect — treat on probability and timing, not on early symptoms.

Acetaminophen (paracetamol) Critical

Key: Biggest silent killer. Plot a level drawn ≥4 h post-ingestion on the Rumack-Matthew nomogram (US treatment line 150 µg/mL at 4 h). For a concerning acute overdose, start NAC while awaiting results if testing would delay treatment beyond 8 h. Unknown timing needs the poison-centre pathway, not the nomogram. For repeated supratherapeutic ingestion spanning >24 h, use acetaminophen concentration and AST/ALT to decide NAC; do not use the nomogram. High-risk exposure (≥30 g or above the high-risk nomogram line) requires toxicology advice. Continue NAC until clinical and laboratory stopping criteria are met, not merely until a fixed infusion ends. SNAP 12 h NAC is a UK regimen; US/Canada use their 2023 consensus pathway.

Opioids Critical

Key: Pinpoint pupils + respiratory depression → titrate naloxone to ventilation, not wakefulness.

Tricyclic antidepressants / sodium-channel blockers Critical

Key: QRS ≥100–110 ms → sodium bicarbonate immediately; anticipate sudden deterioration.

Salicylates Critical

Key: Tinnitus, hyperventilation, mixed acid-base picture — alkalinize serum/urine, prepare for hemodialysis.

Carbon monoxide Critical

Key: Whole household, headache, normal SpO₂ — CO-oximetry, high-flow O₂ ± hyperbaric per criteria.

Organophosphates / nerve agents Critical

Key: SLUDGE, pinpoint pupils — atropine (lots) + pralidoxime; protect staff.

Sympathomimetics / serotonin syndrome Emergent

Key: Hyperthermia + agitation + clonus — benzodiazepines, active cooling. Avoid physical restraint as the only strategy.

Toxic alcohols (methanol / ethylene glycol) / alcohol withdrawal Emergent

Key: Anion-gap acidosis, visual change (methanol) — fomepizole, dialysis planning.

Tick what your patient has — the banner updates as you go.

What, when, how much, why (suicidal vs accidental vs recreational)

Co-ingestants — always ask; ethanol and polypharmacy dominate

Empty containers, notes, access to others’ medications; extended-release products

Chronic medications and occupational exposures

ABCDE with airway priority; GCS and pupils

Vital-sign fingerprint

sympathomimetic vs cholinergic vs sedative-hypnotic vs anticholinergic vs opioid

Skin

sweating, dry (anticholinergic), needle tracks

Odor

bitter almond, garlic (organophosphate), acetone

Seizure activity, temperature (hyperthermia = emergency)

Bedside

  • Glucose (never delay), ECG (QRS/QT), SpO₂ + CO-oximetry when relevant
  • Activated charcoal within ~1 h for selected agents if the airway is protected; later for anticholinergics/delayed-release — call poison centre

Labs

  • Paracetamol and salicylate levels in all deliberate overdoses (and when history is incomplete)
  • ABG/VBG, electrolytes, anion and osmolar gap, lactate, glucose
  • LFTs (late for paracetamol), INR, CK for rhabdo

Imaging / antidotes

  • CXR for aspiration; CT if trauma/fall
  • Naloxone, NAC, sodium bicarbonate, fomepizole, atropine + pralidoxime, high-dose insulin for CCB/BB — know kit location and call poison centre
Medication safety reminder

Use this as a first-pass prompt; verify all medications, doses, concentrations, contraindications, weight, pregnancy status, and local protocols before administration.

Check indication, allergy, route, renal/hepatic risk, interactions, monitoring, and local formulary.

Discharge

  • Awake, below-treatment paracetamol level on a timed 4 h sample (single acute ingestion), completed observation window for the agent, and safe for psychiatric assessment if needed.

Admit (monitored bed)

  • NAC in progress, delayed-release or staggered ingestions, short-acting agents under observation, self-harm safety planning.

ICU

  • Intubated/airway-compromised, pressors, seizures, hyperthermia, hemodialysis (salicylates, methanol, ethylene glycol, lithium), severe TCA cardiotoxicity.

Use objective reassessment and the local pathway.

Before the next decision · reassess and hand over

Use these learning prompts with the presentation’s pathway. They are not discharge criteria.

  1. Reassess: compare symptoms, observations and examination with the initial assessment and response to treatment.
  2. Warning signs for Poisoning & Overdose:
    • Falling GCS or failing airway reflexes
    • QRS widening or new arrhythmia
    • Seizure, hyperthermia, or severe agitation
    • Metabolic acidosis or rising lactate
    • Hypotension unresponsive to fluids
    • Paracetamol presentation that will miss the 8 h NAC window if you wait for a level
  3. Reconsider: check unresolved findings and alternative explanations, including the pitfalls below.
  4. Escalate: communicate deterioration, uncertainty or needs beyond the current setting.
  5. Plan the transition: identify outstanding results, responsibility for follow-up, patient understanding and specific return advice.
Review this presentation’s disposition pathway →Practice a handover →

Clinical Pearls

  • Toxidrome first: vitals, pupils, skin, bowel sounds, temperature.
  • Paracetamol in every deliberate overdose — silent until day 2–3.
  • Naloxone is titrated to ventilation, not to a GCS of 15.
  • QRS ≥100–110 ms in a possible TCA/sodium-channel blocker = bicarbonate now.

Pitfalls

  • A declining GCS in a “stable” overdose precedes the crash — reassess continuously.
  • A paracetamol level drawn before 4 h is not interpretable on the nomogram. Staggered, repeated, and unknown-time ingestions are treated empirically — the nomogram does not apply.
  • Do not give flumazenil in undifferentiated, mixed, or chronic benzodiazepine overdose (seizures, withdrawal). A limited role remains for iatrogenic, benzodiazepine-naive procedural sedation (AHA 2023 toxicology update).
  • QRS widening with hypotension in suspected sodium-channel blockade warrants bicarbonate, resuscitation and poison-centre input.
  • Never delay dextrose for thiamine.
  • Call the poison centre early for high-risk, unknown, or multi-agent ingestions.
PRACTICE REFRESHER

Rapid recall

Test your first action and the dangerous diagnoses before revealing the answer.

01 · First move

Before you scroll, what needs to happen first?

02 · Immediate threats

Name at least two diagnoses that cannot wait.

PRIVATE TO THIS DEVICE

Your learning note

Capture a weak point, a teaching pearl, or a question to take to your next shift.

Review schedule starts when marked reviewed
Altered Mental StatusComa & Depressed LOCSeizuresAgitation & Suicidal IdeationHeat Stroke & HypothermiaECG Guide

Selected guidance · source check 2026-09-07. These 2 source links support selected teaching points, not a complete review of this topic. Check population, setting and local protocol before applying a recommendation.

Exposure and observation

The substance, recurrence and clinical course affect treatment and monitoring needs. Use substance-specific guidance and toxicology advice rather than one fixed observation period.

Source and scope

Supporting teaching points checked 2026-09-10. This is an educational synthesis, not an independently peer-reviewed protocol.

AHA special circumstances: opioid poisoning (2025)

Confirm patient context, full recommendations and local policy. External sources need an internet connection.

  • Rosen’s Emergency Medicine, 10th ed. (2023) — toxicology
  • Dart RC et al. Management of acetaminophen poisoning in the US and Canada: a consensus statement. JAMA Netw Open 2023
  • RCEM/NPIS 2023 SNAP NAC regimen (UK default)
  • AHA 2023 focused update: cardiac arrest or life-threatening toxicity due to poisoning
  • Goldfrank’s Toxicologic Emergencies
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