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Paracetamol
Acetaminophen · Hepatotoxic
HIGH RISK▼
Toxic Doses
Toxic (adult)>150 mg/kg or >7.5g single dose
Potentially fatal>250 mg/kg or >15–25g
Child toxic>150 mg/kg
Max therapeutic1g QDS (4g/24h adult)
Mechanism
PrimarySaturates conjugation pathways → NAPQI accumulates → hepatocellular necrosis
Zone 3Centrilobular necrosis — peak damage 72–96h
Clinical Timeline
0–24hOften asymptomatic, N&V, malaise
24–72hRUQ pain, rising LFTs, PT prolongation
72–96hPeak hepatotoxicity — jaundice, coagulopathy, encephalopathy
>96hRecovery OR acute liver failure
Prehospital Management
  1. Time of ingestion — critical for treatment decision
  2. Activated charcoal if <1h post-ingestion and airway protected
  3. IV access, 12-lead if co-ingestion suspected
  4. Pre-alert ED: paracetamol OD, time, estimated dose
  5. Do NOT delay transport for charcoal
In-hospital: Paracetamol level at 4h plotted on Rumack-Matthew nomogram. IV NAC (Parvolex) highly effective if early. Staggered OD — standard nomogram not applicable; specialist advice.
High risk for toxicity at lower doses: alcohol excess, malnutrition, enzyme-inducing drugs (carbamazepine, rifampicin, phenytoin), HIV, anorexia.
Opioids
Morphine · Heroin · Codeine · Fentanyl · Tramadol · Oxycodone
ANTIDOTE▼
Toxidrome — Classic Triad
Pinpoint pupils · Reduced/absent respirations · Reduced consciousness
GCS ↓, RR <12, SpO₂ ↓, cyanosis, hypotension, bradycardia possible
Key Dose Context
Morphine adultToxic from ~30mg; fatal risk >200mg (opioid naive)
CodeineToxic from ~350mg; fatal >800mg — variable CYP2D6 metabolism
Fentanyl~100× morphine potency; patches = large reservoir, slow release
TramadolAtypical — lowers seizure threshold; serotonergic
Prehospital Management
  1. Airway — BVM if RR <8 or SpO₂ not maintained
  2. Naloxone 400mcg IM/IV — titrate to adequate RR (NOT full reversal)
  3. Repeat q2–3min — max 10mg if needed (fentanyl/methadone)
  4. Half-life naloxone (60–90min) shorter than most opioids — re-narcotisation risk
  5. All opioid OD → hospital regardless of apparent recovery
  6. Intranasal naloxone 400–800mcg if IV access delayed
Methadone/buprenorphine: Prolonged half-life — naloxone infusion likely needed in-hospital. Buprenorphine partially naloxone-resistant.
Tramadol: Seizures in addition to resp depression. Treat with benzodiazepines. Naloxone limited effect on non-opioid mechanisms.
Benzodiazepines
Diazepam · Lorazepam · Temazepam · Nitrazepam · Clonazepam
MODERATE▼
Key Points
FatalityLow when taken alone — rarely fatal without co-ingestion
Co-ingestion riskBDZ + alcohol/opioids/TCAs dramatically increases fatality
Diazepam~>700mg alone; >40mg significant CNS depression
Clinical Features
Mild–ModDrowsiness, slurred speech, ataxia, confusion, amnesia
SevereDeep sedation, respiratory depression, hypotension, coma
PupilsNormal or mildly dilated (unlike opioids)
Prehospital Management
  1. Airway management priority — positioning, suction, BVM if needed
  2. IV access, fluids if hypotensive
  3. Monitor SpO₂, RR, GCS closely
  4. Flumazenil NOT routinely recommended prehospital
  5. Activated charcoal if alert, <1h, airway intact
Flumazenil caution: Contraindicated if chronic BDZ use (precipitates withdrawal seizures), suspected TCA co-ingestion (unmasks arrhythmia), or epilepsy. Hospital use only.
Tricyclic Antidepressants
Amitriptyline · Dosulepin · Imipramine · Clomipramine
CRITICAL▼
Toxic Doses
AmitriptylineToxic: >10–20 mg/kg · Potentially fatal: >30–40 mg/kg
DosulepinMost cardiotoxic TCA in OD — particularly dangerous
Rapid onsetDeterioration within 1–2h of ingestion
Mechanism
CardiacNa⁺ channel blockade → wide QRS, VT, VF
CNSSeizures, coma (anticholinergic + direct)
AnticholinergicTachycardia, dry flushed skin, urinary retention, ileus
Alpha blockadeHypotension, vasodilation
ECG Red Flags
QRS >100ms = high risk seizures
QRS >160ms = high risk VT/VF
R wave >3mm in aVR = cardiotoxicity marker
Rightward terminal QRS axis (S1, aVR R wave)
Prehospital Management
  1. 12-lead ECG — QRS width is key prognostic marker
  2. High flow O₂, IV access × 2
  3. Seizures: IV/IM lorazepam 4mg or diazepam 10mg IV
  4. VT/wide complex: Sodium bicarb 8.4% 1–2 mmol/kg IV (if available)
  5. Do NOT give flumazenil
  6. IMMEDIATE pre-alert with ECG findings
  7. Charcoal only if GCS 15, <1h — high aspiration risk
Can deteriorate catastrophically with minimal warning. Apparently stable → arrest within minutes. Early intubation in hospital if deteriorating.
Salicylates (Aspirin)
Aspirin · Topical salicylates · Oil of wintergreen
HIGH RISK▼
Toxic Doses
Mild toxicity150 mg/kg
Moderate150–300 mg/kg
Severe/fatal>500 mg/kg
Oil of wintergreen1ml = ~1.4g salicylate — 1 tsp fatal in child
Clinical Features
EarlyTinnitus, deafness, N&V, diaphoresis
MetabolicResp alkalosis (early) → metabolic acidosis (late)
CNS severeConfusion, seizures, cerebral oedema, coma
OtherHyperthermia, pulmonary oedema, hypoglycaemia
Prehospital Management
  1. IV access — fluids if dehydrated/hypotensive
  2. BM — hypoglycaemia common in children
  3. Activated charcoal if <1h, alert, airway protected
  4. Do NOT intubate electively — hypoventilation worsens acidosis rapidly
  5. Pre-alert: salicylate OD, estimated dose, clinical status
In-hospital: Urinary alkalinisation (sodium bicarb IV). Haemodialysis if level >700mg/L or symptomatic at lower levels.
SSRIs / Serotonin Syndrome
Fluoxetine · Sertraline · Citalopram · Venlafaxine · SNRI
VARIABLE▼
SSRI Overdose Alone
RiskGenerally low fatality when taken alone
FeaturesN&V, drowsiness, tremor, tachycardia, mydriasis
Citalopram/escitalopramHigher cardiotoxicity — QTc prolongation, seizures at lower doses
Serotonin Syndrome Triad
1. Neuromuscular: Clonus (esp. lower limb), hyperreflexia, myoclonus, rigidity
2. Autonomic: Hyperthermia, diaphoresis, tachycardia, hypertension
3. Altered mental status: Agitation, confusion
Hunter CriteriaSerotonergic drug + clonus (inducible/spontaneous/ocular) = serotonin syndrome
Triggers
Common comboSSRI + tramadol, SSRI + linezolid, SSRI + MAOI (severe), SSRI + St John's Wort
Prehospital Management
  1. Remove precipitating agent if identifiable
  2. Benzodiazepines for agitation/rigidity (IV diazepam 10mg)
  3. Active cooling if >39°C — fan, wet towels
  4. 12-lead ECG — QTc prolongation risk
  5. Pre-alert if temp >39°C, seizures, or haemodynamically unstable
In-hospital: Cyproheptadine (serotonin antagonist). Severe cases may require ICU, intubation, paralysis for hyperthermia control.
Beta-Blockers
Propranolol · Atenolol · Bisoprolol · Metoprolol
CARDIAC▼
Key Points
PropranololMost dangerous — lipid soluble, crosses BBB, membrane stabilising (Na⁺ block)
Toxic doseVaries widely by agent and patient tolerance
OnsetUsually within 1–2h; modified release may delay
Clinical Features
CardiacBradycardia, heart block, hypotension, cardiac arrest
CNSDrowsiness, seizures (propranolol), coma
MetabolicHypoglycaemia (esp. children), bronchospasm
Prehospital Management
  1. 12-lead ECG — PR interval, QRS width, rate
  2. IV access, BM glucose
  3. Atropine 500mcg–3mg IV for symptomatic bradycardia
  4. Glucagon 3–5mg IV if available (bypasses β-receptor)
  5. IV fluid bolus for hypotension
  6. Adrenaline for refractory cardiovascular collapse
  7. IMMEDIATE pre-alert — high-dose insulin / lipid emulsion in hospital
In-hospital: High-dose insulin (1 unit/kg bolus + infusion), IV lipid emulsion 20% for propranolol. ECMO in refractory arrest.
Calcium Channel Blockers
Amlodipine · Verapamil · Diltiazem · Nifedipine
CARDIAC▼
Key Points
Verapamil/diltiazemRate-limiting — severe bradycardia and AV block
Amlodipine/nifedipineDihydropyridines — primarily vasodilation, reflex tachycardia
MR preparationsDelayed absorption — symptoms may be delayed 6–12h
Clinical Features
CardiacBradycardia, AV block, hypotension, cardiogenic shock
MetabolicHyperglycaemia (inhibits insulin release)
CNSDizziness, confusion, seizures in severe cases
Prehospital Management
  1. 12-lead ECG — rate and rhythm
  2. IV access × 2, large volume fluid bolus
  3. Atropine for bradycardia (often poorly effective)
  4. Calcium gluconate 10% 10ml IV if available
  5. Adrenaline for refractory shock
  6. Pre-alert all CCB OD — even asymptomatic if MR preparation
In-hospital: HIET (high-dose insulin euglycaemic therapy) is key. IV lipid emulsion, calcium infusion, vasopressors, ECMO.
Digoxin
Cardiac glycoside · Narrow therapeutic index
CARDIAC▼
Key Points
Therapeutic range0.5–2.0 nmol/L — very narrow window
Toxic>2.6 nmol/L (but toxicity can occur within range with electrolyte disturbance)
PotentiatorsHypokalaemia, hypomagnesaemia, hypothyroidism, renal failure dramatically increase toxicity
Acute vs chronicAcute OD (higher dose, N&V early) vs chronic toxicity (lower dose, more insidious) — different presentations
Clinical Features
GIN&V, abdominal pain, anorexia (often first sign)
CardiacBradycardia, any arrhythmia (esp. PAT with block, junctional, VT), AV block
CNSConfusion, visual disturbance (yellow-green halos), fatigue
ElectrolytesAcute: hyperkalaemia (K⁺ >5.5 = severe toxicity marker). Chronic: hypokalaemia common precipitant
ECG Features
TherapeuticReversed tick ST depression, short QT — normal digoxin effect
ToxicBradyarrhythmias, heart block, bidirectional VT (classic but rare), AF with slow ventricular rate
Prehospital Management
  1. 12-lead ECG and continuous monitoring
  2. IV access — do NOT give calcium (may precipitate refractory VF with digoxin toxicity)
  3. Atropine for symptomatic bradycardia/block
  4. DC cardioversion for VF/pulseless VT (use lowest effective energy)
  5. Activated charcoal if acute ingestion <1h, alert
  6. Pre-alert: digoxin toxicity suspected, ECG findings, K⁺ if known
In-hospital: Digoxin-specific antibody fragments (Digifab/DigiFab) — definitive treatment. Dose calculated from estimated ingested dose or serum level. Correct hypokalaemia carefully.
Avoid calcium IV — may cause stone heart (irreversible systolic arrest) in digoxin toxicity. Avoid class 1a antiarrhythmics.
Lithium
Lithium carbonate · Narrow therapeutic index
DELAYED▼
Toxic Levels
Therapeutic0.4–1.0 mmol/L (maintenance); 0.8–1.2 (acute treatment)
Mild toxicity1.5–2.0 mmol/L
Moderate2.0–2.5 mmol/L
Severe>2.5 mmol/L — haemodialysis likely needed
Acute vs chronicChronic toxicity = worse neurological outcome at same level than acute OD
Precipitants of Toxicity
DehydrationReduces renal Li⁺ excretion — most common cause of toxicity
NSAIDsRaise lithium levels significantly
ACE inhibitorsAlso raise lithium levels
DiureticsThiazides especially — reduce excretion
Infection/vomitingFluid loss → toxicity in stable patient
Clinical Features (Severity Progression)
MildNausea, tremor, thirst, polyuria, mild confusion
ModerateCoarse tremor, ataxia, dysarthria, drowsiness, muscle twitching
SevereSeizures, coma, rigidity, hyperthermia, cardiovascular collapse, irreversible neurological damage (SILENT syndrome)
Prehospital Management
  1. IV access — IV 0.9% NaCl (NOT dextrose) — promotes renal excretion
  2. Seizures: benzodiazepines
  3. Activated charcoal NOT effective for lithium
  4. ECG — QTc prolongation, T wave changes
  5. Pre-alert: lithium toxicity, level if known, neurological status
In-hospital: Serum lithium levels. Haemodialysis for severe toxicity or level >2.5 with symptoms. Whole bowel irrigation for sustained-release tablets.
Antipsychotics
Quetiapine · Olanzapine · Haloperidol · Risperidone · Clozapine
VARIABLE▼
Key Agents — Risk Profile
QuetiapineVery common OD — sedation, hypotension, QTc prolongation, tachycardia. Toxic from ~2g
ClozapineHighest risk — seizures, agranulocytosis, myocarditis, severe sedation, hypersalivation
HaloperidolExtrapyramidal symptoms, QTc prolongation, less sedation
OlanzapineSedation, metabolic effects, some QTc prolongation
Clinical Features
CNSSedation, coma, seizures (clozapine especially)
CardiacQTc prolongation → torsades de pointes, hypotension
AnticholinergicTachycardia, dry mouth, urinary retention, ileus
ExtrapyramidalDystonia, akathisia, rigidity (acute reaction or NMS)
Neuroleptic Malignant Syndrome (NMS)
Tetrad: Hyperthermia · Rigidity (lead pipe) · Altered consciousness · Autonomic instability
Can occur at therapeutic doses. Distinguish from serotonin syndrome — rigidity more pronounced, slower onset, no clonus.
Prehospital Management
  1. Airway — sedation risk is significant
  2. 12-lead ECG — QTc monitoring essential
  3. IV access, IV fluid if hypotensive
  4. Acute dystonia: procyclidine 5–10mg IM/IV (if available) or benzatropine
  5. NMS: active cooling, benzodiazepines, rapid transport
  6. Activated charcoal if <1h, alert, airway intact
In-hospital: Magnesium sulphate for torsades. NMS: dantrolene (muscle relaxant), bromocriptine (dopamine agonist).
Anticonvulsants
Carbamazepine · Phenytoin · Valproate · Lamotrigine
VARIABLE▼
Key Agents
CarbamazepineCardiotoxic (Na⁺ channel block like TCA), wide QRS, anticholinergic, seizures, cyclic coma. MDAC beneficial.
PhenytoinCardiac arrhythmia (IV) — give slowly. Nystagmus, ataxia, drowsiness, paradoxical seizures.
ValproateHepatotoxicity, hyperammonaemia, pancreatitis, tremor, coagulopathy. Toxic >200 mg/kg.
LamotrigineSeizures, cardiac conduction disturbance (Na⁺ channel). Similar ECG to TCA.
Prehospital Management
  1. 12-lead ECG — carbamazepine and lamotrigine can widen QRS
  2. Seizures: benzodiazepines first line
  3. Activated charcoal if <1h, alert — MDAC useful for carbamazepine and phenobarbitone in hospital
  4. IV access, monitor GCS
  5. Pre-alert: agent, dose, ECG findings, seizure activity
Enzyme-inducing drugs (carbamazepine, phenytoin, phenobarbitone, primidone) increase paracetamol toxicity at lower doses — important when managing co-ingestions.
Organophosphates / Nerve Agents
Pesticides · Insecticides · Chemical agents
SCENE SAFETY▼
Scene safety: Risk of secondary contamination. PPE before patient contact. Consider HAZMAT decontamination for significant exposure.
Mechanism
AChE inhibitionAcetylcholinesterase irreversibly inhibited → ACh accumulates at all synapses
Toxidrome — SLUDGE / DUMBELS
Muscarinic (SLUDGE): Salivation, Lacrimation, Urination, Defecation, GI distress, Emesis
+ Miosis (pinpoint pupils), bronchospasm, bradycardia, secretions
Nicotinic: Muscle fasciculations, weakness, paralysis (respiratory muscles)
CNS: Anxiety, seizures, coma
Prehospital Management
  1. Remove from exposure — decontaminate (remove clothing, copious water)
  2. Airway — suction secretions, BVM/intubation for respiratory failure
  3. Atropine 2mg IV q5min — titrate to dry secretions (NOT to pupil/HR) — may need very large doses (20–100mg)
  4. Pralidoxime (2-PAM) — hospital/specialist. Reactivates AChE if given within hours. Ineffective once ageing occurs.
  5. Seizures: benzodiazepines
  6. IMMEDIATE pre-alert — organophosphate exposure, decontamination status
Atropine endpoint is dry secretions and adequate ventilation — NOT tachycardia or pupil dilation. Don't under-dose.
Iron
Ferrous sulphate · Ferrous fumarate · Iron supplements
PAEDIATRIC RISK▼
Toxic Doses (elemental iron)
Non-toxic<20 mg/kg elemental iron
Mild–mod toxic20–60 mg/kg
Severe>60 mg/kg — potentially fatal
CalculationFerrous sulphate 200mg = 65mg elemental iron (32%)
Clinical Phases
Phase 1 (0–6h)GI toxicity — N&V, bloody diarrhoea, abdominal pain
Phase 2 (6–24h)Apparent improvement — deceptive
Phase 3 (>12h)Metabolic acidosis, shock, hepatic failure, coagulopathy
Prehospital Management
  1. Calculate dose if possible — tablet count, strength
  2. IV access, fluids for dehydration/shock
  3. Activated charcoal NOT effective for iron
  4. All significant ingestions → hospital
In-hospital: AXR (radio-opaque tablets), serum iron levels, desferrioxamine chelation if severe.
Carbon Monoxide
CO poisoning · Combustion products
SCENE SAFETY▼
Scene safety first. Do NOT enter without HFRS clearance if CO source active. Multiple casualties with similar symptoms = suspect CO.
COHb Levels & Features
10–20%Headache, dizziness, nausea — often misdiagnosed as flu/migraine
20–40%Severe headache, confusion, visual disturbance, syncope
40–60%Seizures, coma, cardiovascular compromise
>60%Fatal
SpO₂FALSELY NORMAL on standard pulse oximetry — unreliable
Prehospital Management
  1. Remove from source — own safety first
  2. 15L/min O₂ via NRM — even if SpO₂ appears normal
  3. 100% O₂ halves COHb half-life (~5h → 60–80min)
  4. 12-lead ECG — myocardial injury common
  5. BM — hypoglycaemia possible
  6. Pre-alert: CO exposure, GCS, symptoms, COHb if measured
  7. All symptomatic patients to hospital — consider HBO
HBO indications: LOC, COHb >25%, neurological features, cardiac involvement, pregnancy.
Alcohols
Ethanol · Methanol · Ethylene glycol
COMMON▼
Ethanol
Toxic BAC>200mg/dL significant impairment; >400mg/dL potentially fatal
Key riskAspiration of vomit — maintain airway
Wernicke'sChronic alcohol + confusion/ataxia/ophthalmoplegia → Pabrinex IV BEFORE glucose
Methanol / Ethylene Glycol
Suspect if: Intoxicated but low/no alcohol smell · Visual symptoms (methanol) · Renal failure (EG/antifreeze) · Severe metabolic acidosis disproportionate to presentation
MethanolVisual disturbance → blindness, metabolic acidosis — fatal at small doses
Ethylene glycolRenal failure, calcium oxalate crystals, metabolic acidosis
Prehospital Management
  1. Airway — lateral position, suction
  2. BM — hypoglycaemia common esp. children
  3. Wernicke's: Pabrinex BEFORE glucose
  4. Methanol/EG: no prehospital antidote — rapid transport, pre-alert
In-hospital: Fomepizole (ADH inhibitor) for methanol/EG. Haemodialysis in severe cases.
mg/kg Dose Calculator
Patient Weight
Weight kg
Dose taken mg
Drug
Quick mg/kg Reference
DrugSub-toxicToxicSevere/Fatal
Paracetamol<75 mg/kg>150 mg/kg>250 mg/kg
Aspirin<150 mg/kg150–300>500 mg/kg
Iron (elemental)<20 mg/kg20–60 mg/kg>60 mg/kg
Amitriptyline<5 mg/kg10–20 mg/kg>30 mg/kg
Sodium valproate<100 mg/kg100–200 mg/kg>400 mg/kg
Activated charcoalAdult: 50g · Child: 1 g/kg (max 50g)
Thresholds are guidelines — individual factors (enzyme inducers, liver disease, renal failure, staggered ingestion) alter risk significantly. Always consider clinical context.
Naloxone / Drug Dose Reference
DrugDoseRoute / Notes
Naloxone400 mcgIV/IM titrated; IN 400–800mcg; repeat q2–3min
Diazepam (seizures)10 mg adult / 0.3 mg/kg childIV slow push; PR 10–20mg if no IV
Lorazepam (seizures)4 mg adult / 0.1 mg/kg childIV/IM preferred
Atropine (OP/bradycardia)500mcg–2mg, repeat q5minIV; titrate to secretions in OP
Glucagon (β-blocker)3–5 mg IVRepeat if needed; short duration
Glucose 10%150–200 ml IVFor hypoglycaemia; more if sulphonylurea OD
Adrenaline (cardiac arrest)1 mg IV q3–5minStandard ALS; consider higher in toxicology arrest
Sodium bicarb 8.4%1–2 mmol/kg IVTCA cardiotoxicity / wide QRS. 1ml = 1mmol
Hydroxycobalamin5g IV over 15minCyanide — fire casualties
Activated Charcoal — Time & Indication
Core principle: Activated charcoal (AC) adsorbs toxins in the GI tract, reducing absorption. Efficacy drops sharply after 1 hour. Airway protection is mandatory before administration.
Timing — Window of Benefit
▼
<1 hour post-ingestion
Greatest benefit. Strong indication if airway intact and agent is charcoal-sensitive. Adult: 50g; Child: 1g/kg (max 50g).
1–2 hours post-ingestion
Benefit diminishing but may be worthwhile for large ingestions or agents with slow GI absorption.
2–4 hours post-ingestion
Generally not recommended unless modified-release preparation or enterohepatic recirculation. Specialist advice.
>4 hours post-ingestion
Rarely beneficial. Exceptions: modified-release preparations where absorption still ongoing.
Multiple-dose AC (MDAC)
Repeated doses for: theophylline, phenobarbitone, carbamazepine, quinine, dapsone. Hospital use.
Contraindications
▼
Absolute:
• Unprotected airway / GCS <15 (caution) — intubated only if significantly reduced
• Corrosives / caustics — worsens injury
• Hydrocarbons / petroleum products — aspiration risk
• Intestinal obstruction or absent bowel sounds
Agents NOT Adsorbed by AC
MetalsIron, lithium, lead, mercury
AlcoholsEthanol, methanol, ethylene glycol
ElectrolytesSodium, potassium, magnesium
Acids/AlkalisCaustic substances
CyanidePoorly adsorbed — specific antidote needed
Good Candidates for AC
▼
Well Adsorbed
ParacetamolExcellent — within 1h
AspirinGood — within 1h
TCAsGood — within 1h (airway critical)
BenzodiazepinesGood — within 1h
AntipsychoticsGood — within 1h
AnticonvulsantsGood — carbamazepine also benefits from MDAC
Most pharmaceuticalsAdsorbed well if given early
Common Antidotes — Quick Reference
AntidoteForRoute / Notes
NaloxoneOpioids (all)IV/IM/IN — titrate to RR. Short-acting vs most opioids
NAC (Parvolex)ParacetamolIV infusion — 21h regimen. Highly effective if early
FlumazenilBenzodiazepinesIV only — many contraindications. Not routine prehospital
Sodium bicarbonateTCAs, salicylates, lamotrigineIV bolus for TCA arrhythmia. Urinary alkalinisation for salicylates
GlucagonBeta-blockersIV — bypasses β-receptor. Short duration
Calcium gluconateCCBs, hyperkalaemia, HFIV slow push — modest benefit CCB OD. AVOID in digoxin toxicity
AtropineOrganophosphates, bradycardiaIV — large doses in OP (titrate to secretions, not HR)
Pralidoxime (2-PAM)OrganophosphatesIV — hospital. Reactivates AChE if given early (before ageing)
Digoxin-Fab (DigiFab)Digoxin toxicityIV — hospital. Dose from ingested dose or serum level
DesferrioxamineIronIV infusion — hospital. Chelates free iron
HydroxycobalaminCyanideIV — 5g over 15min. Pre-hospital use in fire casualties
FomepizoleMethanol, ethylene glycolIV — hospital. ADH inhibitor
Phytomenadione (Vit K)Warfarin/anticoagulantsIV/oral — slow onset. PCC for immediate reversal
Glucose 10%Hypoglycaemia (sulphonylureas, insulin)IV infusion — prolonged monitoring for sulphonylureas
Glucagon 1mgHypoglycaemia (no IV access)IM — slower onset
Thiamine (Pabrinex)Wernicke's / alcoholIV — give BEFORE glucose in suspected Wernicke's
Lipid emulsion 20%Lipid-soluble drugs (propranolol, LA toxicity)IV — hospital/specialist. LAST LINE
High-dose insulinBeta-blockers, CCBsIV — hospital. HIET protocol
CyproheptadineSerotonin syndromeOral — hospital. Serotonin antagonist
DantroleneNMS, malignant hyperthermiaIV — hospital. Muscle relaxant
Oxygen 100%Carbon monoxideNRM 15L/min. HBO if severe
ProcyclidineAcute dystonia (antipsychotics)IM/IV 5–10mg
Key Clinical Questions
On Scene — Every OD
▼
  • What was taken? (substance, formulation, brand)
  • How much? (tablets — count remaining, estimate taken)
  • When exactly? (time of ingestion — single or staggered)
  • Anything else taken? (including alcohol, recreational drugs)
  • Any vomiting since ingestion? (how many times, tablets visible)
  • Any treatment taken since?
  • Is this intentional? (safety concerns, psychiatric history)
  • Any prior overdoses?
  • Regular medications and medical history (enzyme inducers, liver disease, renal failure)
  • Weight of patient (dose/kg calculations)
  • Access to other medications in the house?
Prescription Review Questions
▼
  • When was prescription last dispensed and what quantity?
  • Any other prescribers / online pharmacy / repeat prescriptions?
  • Enzyme-inducing drugs prescribed? (increases paracetamol toxicity at lower doses)
  • Anticoagulants? (important for co-ingestions)
  • MAOIs? (severe serotonin syndrome risk with many common drugs)
  • NSAIDs / ACE inhibitors? (raise lithium levels)
  • Any hospital discharge medications recently started?
Scene Assessment
▼
  • Empty packets/bottles — how many, what strength?
  • Smell of alcohol on breath or in environment
  • Drug paraphernalia present
  • Pill count at scene — tablets in pack vs remaining
  • Suicide note?
  • CO detector alarm? Multiple similar casualties?
  • Combustion appliances, blocked flues, running vehicles?
  • Other people in the house potentially exposed?
  • Agricultural/industrial chemicals present? (OP risk)
Specific Agent Questions
▼
Paracetamol
  • Taken all at once or staggered over time?
  • Heavy alcohol use or liver disease?
  • Malnourished or anorexic?
  • Taking enzyme inducers (carbamazepine, rifampicin, phenytoin, St John's Wort)?
Opioids
  • Prescribed or illicit? If illicit — fentanyl contamination likely?
  • Opioid naive or tolerant?
  • Methadone/buprenorphine — dose and last taken?
  • Any fentanyl patch use or found on scene?
Lithium
  • Any recent illness, vomiting, diarrhoea or dehydration?
  • NSAIDs, ACE inhibitors or diuretics started recently?
  • Last lithium level and when?
Unknown Substance
  • What toxidrome fits — opioid / cholinergic / anticholinergic / sympathomimetic / sedative?
  • Recreational drugs — new psychoactive substances?
  • Pill or powder? Any visible tablet markings?
When to Refer / Admit
Immediate Pre-Alert Criteria
▼
Pre-alert for any of the following:
  • GCS ≤13 or deteriorating consciousness
  • Respiratory compromise (RR <10, SpO₂ <94% on O₂, apnoea)
  • Haemodynamic instability (SBP <90, HR <50 or >130)
  • Seizure activity (convulsing or post-ictal)
  • Significant ECG changes (wide QRS, QTc prolongation, arrhythmia)
  • Known TCA, beta-blocker, CCB, digoxin, anticonvulsant, or antipsychotic ingestion
  • Suspected cyanide or organophosphate poisoning
  • CO with any neurological symptoms or COHb >25%
  • Paediatric ingestion of any quantity of adult medication
  • Pregnancy with any significant ingestion
  • NMS or serotonin syndrome with hyperthermia
All OD → Hospital
▼
Default position: Virtually all deliberate self-poisoning requires hospital assessment — medical management AND psychiatric/safeguarding assessment. Do not convey to GP.
Specific "Always Admit" Agents
  • Paracetamol — even asymptomatic; levels not meaningful before 4h
  • TCAs — any ingestion above therapeutic dose
  • Modified-release preparations — symptoms may be delayed 6–24h
  • Beta-blockers / CCBs — delayed onset possible
  • Opioids — re-narcotisation risk after naloxone
  • Iron — asymptomatic phase 2 is deceptive
  • Methadone — very long half-life
  • Lithium — delayed neurological deterioration
  • Digoxin — arrhythmia may be delayed
  • Any child with adult medication ingestion
  • Co-codamol or compound analgesics — often underestimated paracetamol component
Potential Refer to GP (Low Risk Only)
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Occasionally appropriate for accidental ingestion of known non-toxic amount with ALL of the following:
Agent
Known, low-toxicity substance
Dose
Below toxic threshold with certainty
Intentionality
Accidental only — no self-harm concerns
Symptoms
Currently asymptomatic
Timing
Window for intervention passed AND not delayed-release
Social
Responsible adult present, able to monitor
When in doubt — convey. Risk of under-triaging significantly outweighs inconvenience of unnecessary ED attendance.
NPIS / Toxbase Contact
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NPIS Numbers
Clinical advice0344 892 0111 (24h — clinicians only)
Toxbasewww.toxbase.org — HCPC/NMC login
When to callUnknown substance, unusual presentation, paediatric, unusual dose, unclear management
⚠ Clinical Reference Tool — Aide-memoire for qualified clinicians. Always verify critical doses and management against Toxbase/NPIS. Not a substitute for clinical judgement, local protocols, or specialist advice. Drug doses and guidelines subject to change.