Version July 2025
| To obtain emergency consultation with a medical toxicologist, in the United States, call 1-800-222-1222 for the nearest regional poison control center. Contact information for poison centers around the world is available at the WHO website and in the UpToDate topic on regional poison centers (society guideline links). |
| Clinical syndromes |
| Acute cholinergic toxicity |
| Generally manifests in minutes to hours. |
| Evidence of cholinergic excess (SLUDGE-BBB). |
| SLUDGE = Salivation, Lacrimation, Urination, Defecation, Gastric Emptying. |
| BBB = Bradycardia, Bronchorrhea, Bronchospasm. |
| Acute nicotinic toxicity includes fasciculations and muscle paralysis (also transient early tachycardia and hypertension, especially in children). |
| Respiratory insufficiency can result from muscle weakness, decreased central drive, increased secretions, and bronchospasm. |
| Intermediate (neurologic) syndrome |
| Occurs 24 to 96 hours after exposure. |
| Bulbar, respiratory, and proximal muscle weakness are prominent features. |
| Generally resolves in 1 to 3 weeks. |
| Organophosphate-induced delayed peripheral neuropathy (OPIDN) |
| Usually occurs several weeks after exposure to one of the following: chlorpyrifos, leptophos, malathion, merphos, mipafox, trichlorfon, triorthocresyl phosphate. |
| Primarily motor involvement (flaccid weakness of the lower extremities, which ascends to involve the upper extremities). |
| May resolve spontaneously, but can result in permanent neurologic dysfunction (upper motor neuron syndrome with spasticity of the lower extremities). |
| Diagnostic evaluation of acute toxicity |
| Poisoning is a clinical diagnosis based on presence of cholinergic symptoms (SLUDGE-BBB). |
| Atropine challenge if diagnosis is in doubt (1 mg IV once in adults, 0.01 to 0.02 mg/kg IV once in children). |
| Absence of anticholinergic signs (tachycardia, mydriasis, decreased bowel sounds, dry skin) following atropine administration strongly suggests poisoning with organophosphate or carbamate. |
| Many organophosphates have a characteristic petroleum or garlic-like odor. |
| Try to accurately identify the involved agent; dimethyl compounds (eg, monocrotophos, methyl parathion, dimethoate, dichlorvos, phosphamidon) are associated with worse outcome and require rapid initiation of oxime therapy; diethyl compounds (eg, chlorpyriphos, parathion, quinalphos) may exhibit delayed toxicity and require prolonged treatment. |
| Draw blood sample for measurement of RBC acetylcholinesterase activity, if available, to confirm diagnosis. |
| Treatment of acute toxicity |
| Deliver 100% oxygen via facemask; early tracheal intubation often required; for rapid sequence intubation, use nondepolarizing neuromuscular blocking agents (eg, rocuronium) instead of succinylcholine; larger doses are often required. |
| Decontamination if ingestion within 1 hour, give activated charcoal without sorbitol 50 g orally once (1 g/kg orally once in children; maximum 50 g) unless airway not protected or other contraindication. For topical exposure, aggressive dermal and ocular irrigation as needed. Bag and discard clothing. |
| Atropine 2 to 5 mg IV/IM/IO bolus (0.05 mg/kg IV/IM/IO in children; maximum 2 mg per dose). Can start with 1 to 2 mg IV/IM/IO bolus in adults if mild toxicity (ie, miosis and severe rhinorrhea but no other symptoms). |
| Escalate (double) dose every 3 to 5 minutes until bronchial secretions and wheezing stop. |
| Tachycardia and mydriasis are not contraindications to atropine use nor appropriate markers for therapeutic improvement. |
| In severe poisonings, hundreds of milligrams by bolus and continuous infusion may be needed over several days.* |
| Inhaled (nebulized) ipratropium 0.5 mg with parenteral atropine may be helpful for bronchospasm; may repeat. |
| Pralidoxime (2-PAM) 30 mg/kg IV bolus (20 to 50 mg/kg IV in children), maximum single dose 2 g, over 15 to 30 minutes. |
| Follow with continuous infusion at 8 to 10 mg/kg/hour, maximum 1 g/hour (10 to 20 mg/kg/hour in children; maximum 500 mg/hour). |
| If no IV access, give pralidoxime 600 mg IM (15 mg/kg in children <40 kg). Repeat as needed every 15 minutes for up to 3 doses. |
| Pralidoxime must be given with atropine. |
| Benzodiazepine in patient with seizures, agitation, coma, apnea, or neuromuscular paralysis. |
| Diazepam 10 mg IV (0.1 to 0.2 mg/kg IV in children), repeat as necessary every 3 to 5 minutes if seizures recur. |
IM: intramuscular; IO: intraosseous; IV: intravenous; RBC: red blood cells.
* Refer to UpToDate topic on organophosphate poisoning for dosing of atropine continuous infusion.
