🚑 EmergencyToxicology / EmergencyStudentInternResident

Organophosphate Poisoning

Also known as: OP poisoning · pesticide poisoning · cholinergic crisis · insecticide poisoning

Cholinesterase-inhibitor (pesticide) poisoning causing a cholinergic crisis. Atropine plus an oxime and supportive care are life-saving; very common in rural India.

Source · Reviewed 2026-08-15 · v1.0— AI-assisted draft — verify against the cited guideline / poison centre before clinical use.

⚕️ Education only — not medical advice. Verify against the latest official guideline and your local protocol; confirm every drug dose against the cited source before clinical use.

Who gets it

Agricultural/occupational exposure and deliberate self-harm ingestion; children with accidental exposure.

Red flags — escalate / refer

Cholinergic crisis — SLUDGE/DUMBELS (salivation, lacrimation, urination, defecation, GI upset, emesis) plus bronchorrhoea/bronchospasm, bradycardia and pinpoint pupils, with fasciculations, weakness or seizures → resuscitate and atropinise.
Respiratory failure from secretions/weakness → ventilate.
Intermediate syndrome (24–96 h): proximal weakness and respiratory failure.

Work-up / diagnosis

1Clinical diagnosis from the toxidrome plus the exposure history (a solvent/garlic smell may be present).
2The therapeutic end-point is drying of secretions and a clear chest — not the pupils.
3Plasma/RBC cholinesterase supports the diagnosis but must not delay treatment.

Management — overview

ABC + high-flow oxygen; protect the airway (copious secretions); decontaminate (remove clothing, wash skin) with staff wearing PPE.
ATROPINE is the priority: give escalating (doubling) IV boluses until 'atropinised' (chest clear, adequate HR/BP), then a maintenance infusion.
Give PRALIDOXIME (an oxime) early — it reactivates acetylcholinesterase and helps nicotinic (muscle) features.
Control seizures/agitation with a benzodiazepine; ventilate for respiratory failure; watch for the intermediate syndrome.

In-depthFull dosing & advanced protocol

Drug dosing

Atropine

Reverse muscarinic effects (priority)

Adult dose: 2–5 mg IV, DOUBLE every ~5 min until atropinised (clear chest, dry secretions); then an infusion
Paediatric: 0.05 mg/kg IV, escalate similarly
Route: Intravenous

Caution: Titrate to a clear chest — NOT to pupil size; large cumulative doses are often needed.

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

Pralidoxime (2-PAM, an oxime)

Reactivate acetylcholinesterase

Adult dose: Loading dose then infusion per protocol; give early with atropine
Route: Intravenous

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

Benzodiazepine (diazepam/lorazepam)

Agitation / seizures

Adult dose: IV, titrated
Route: Intravenous

WHOWHO Model List of Essential Medicines (electronic EML) (2025 (24th)) ↗

End-points, oximes & later syndromes

Atropinisation targets: clear chest on auscultation, heart rate/BP adequate, dry axillae, pupils no longer the guide.
Give the oxime early; benefit is greatest before enzyme 'ageing'. Carbamate poisoning is similar but usually milder and self-limiting (oxime often unnecessary).
Watch for the intermediate syndrome (respiratory failure at 24–96 h) and delayed polyneuropathy; protect staff from secondary contamination.

ICMRStandard Treatment Workflows (STWs), India — Dept. of Health Research & ICMR (2022+) ↗

References

Guidelines change. If something here is out of date, tell us — we keep these current.

🚩 Report outdated / suggest update

More protocols

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👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Atropine

Pralidoxime (2-PAM, an oxime)

Benzodiazepine (diazepam/lorazepam)

📈 End-points, oximes & later syndromes

📚 References

More protocols

👤 Who gets it

🚩 Red flags — escalate / refer

🔎 Work-up / diagnosis

🧭 Management — overview

💊 Drug dosing

Atropine

Pralidoxime (2-PAM, an oxime)

Benzodiazepine (diazepam/lorazepam)

📈 End-points, oximes & later syndromes

📚 References

More protocols

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

End-points, oximes & later syndromes

References

Who gets it

Red flags — escalate / refer

Work-up / diagnosis

Management — overview

Drug dosing

End-points, oximes & later syndromes

References