# Organophosphate Toxicity

Treat suspected organophosphate toxicity as a clinical cholinergic emergency: protect staff, control airway and bronchorrhea, titrate atropine to a clear chest, add an oxime when indicated, and use cholinesterase testing as confirmation rather than a reason to delay resuscitation.

**Clinical question:** How should clinicians rapidly diagnose, stabilize, antidote-treat, and monitor suspected acute organophosphate toxicity?

Updated: 2026-09-16T00:08:04.714361+00:00

## What matters in practice
- Respiratory failure from bronchorrhea and bronchospasm is the principal immediate lethal threat; prioritize airway, oxygenation, ventilation, and secretion control over confirmatory testing. [19][4]
- Titrate atropine to resolution of bronchorrhea and a clear chest rather than to pupil size alone; nerve-agent guidance uses 2 mg IM/IV with dose doubling every 5-10 minutes until clinical endpoints are reached. [3][22]
- Remove contaminated clothing and wash exposed skin with soap and water; perform decontamination while preventing secondary exposure of staff. [22][20]
- Pralidoxime is used with atropine, not instead of atropine; evidence for outcome benefit in adult pesticide poisoning remains uncertain. [3][23]
- Measure serum cholinesterase when available to support the diagnosis and obtain ECG in acute poisoning, but begin antidotal and respiratory treatment on clinical grounds. [21][8]

## Stabilize respiratory cholinergic toxicity before diagnostic confirmation

Treat a compatible exposure and cholinergic syndrome as an antidote-responsive emergency.

Move the patient from the contaminated atmosphere, protect personnel from secondary contamination, remove clothing, and wash exposed skin thoroughly with soap and water. If soap and water are unavailable after suspected nerve-agent skin exposure, dry removal with absorbent material is a fallback measure. [22][20]

Perform immediate airway, breathing, circulation, and neurologic assessment. Give oxygen, establish monitoring and IV access, and provide ventilatory support when bronchorrhea, bronchospasm, coma, seizures, or respiratory muscle weakness compromises ventilation. Early resuscitation with atropine, oxygen, respiratory support, and fluids is recommended to improve oxygen delivery. [3][4][22]

Do not delay atropine for cholinesterase results. In suspected organophosphate toxicity, use serial lung examination and secretion burden as the dominant treatment endpoint: resolution of bronchorrhea is the most important antimuscarinic effect. [3][19]
- Intubate when secretions, hypoxemia, impaired consciousness, or neuromuscular respiratory failure prevents adequate oxygenation or airway protection; continue atropine during airway management. [22][19]
- Treat seizures with a benzodiazepine; diazepam 5 mg IV stat is included in one emergency protocol. [21][22]
- Avoid activated charcoal in patients with a compromised airway or CNS depression because aspiration risk outweighs benefit. [3]

*Immediate priorities in suspected acute organophosphate toxicity. [3][4][22]*

| Problem | Bedside finding | Immediate action | Treatment endpoint |
| --- | --- | --- | --- |
| Airway/ventilation | Bronchorrhea, bronchospasm, hypoxemia, coma, or weakness [19][22] | Oxygen and respiratory support; intubate when ventilation or airway protection is inadequate. [4][22] | Adequate oxygenation and ventilation. [4][22] |
| Muscarinic excess | Wet lungs or persistent bronchial secretions [3] | Start IV/IM atropine and rapidly escalate. [22] | Clear chest with resolution of bronchorrhea. [3][22] |
| Ongoing contamination | Dermal or respiratory exposure [22] | Remove clothing; wash skin with soap and water; protect staff. [22][20] | No ongoing external contamination. [22] |
| Seizure/coma | Convulsions or depressed consciousness [22] | Benzodiazepine and airway-directed supportive care. [21][22] | Seizure control and protected ventilation. [22] |

## Recognize the cholinergic pattern and use tests to support—not postpone—treatment

Exposure history plus a compatible toxidrome drives the first treatment decision.

Suspect acetylcholinesterase-inhibiting organophosphate exposure after pesticide contact, deliberate ingestion, occupational exposure, or a potential nerve-agent event when miosis, diaphoresis, excessive secretions, bronchospasm, bradycardia, diarrhea, fasciculations, or central neurologic toxicity occur together. Organophosphate poisoning follows dermal, inhalational, or oral exposure and may progress to seizures or respiratory failure. [1][19]

Obtain a 12-lead ECG and serum cholinesterase level when available after initial stabilization. Serum cholinesterase testing can support the clinical diagnosis, while ECG identifies associated rhythm or conduction abnormalities that may alter monitoring and resuscitation; neither test should delay atropine or respiratory intervention. [21][3]

Interpret a cholinesterase value in clinical context. Acetylcholinesterase inhibition from organophosphates may recover more slowly than butyrylcholinesterase, creating a cumulative inhibitory effect; serial laboratory values therefore do not substitute for serial respiratory examinations and atropine requirement. [9][8]
- Ask specifically for product name, formulation, route, timing, estimated amount, coingestants, and whether other exposed persons are symptomatic; agent toxicity and exposure route contribute to variable presentation. [2][1]
- Consider carbamate insecticide exposure in the differential because it can produce a similar cholinergic clinical picture. [17][18]
- Do not anchor on isolated miosis or depressed consciousness: bright light can cause small pupils, and opioid exposure can produce miosis with depressed consciousness. [22]

*Clinical findings that change the immediate diagnostic and treatment pathway. [1][19][22]*

| Pattern | Interpretation | Next action |
| --- | --- | --- |
| Bronchorrhea, wheeze, hypoxemia | Life-threatening respiratory cholinergic toxicity; respiratory failure is the major fatal complication. [19] | Immediate atropine titration plus oxygen and ventilatory support. [4][22] |
| Fasciculations or weakness | Nicotinic involvement with risk of respiratory pump failure. [19][11] | Closely reassess ventilation and prepare for assisted ventilation. [11][22] |
| Miosis, diarrhea, bradycardia with secretion excess | Compatible muscarinic cholinergic syndrome. [1][19] | Treat clinically while obtaining exposure history, ECG, and cholinesterase testing. [21][3] |
| Miosis and coma without secretion excess | May be opioid toxicity or another cause rather than isolated organophosphate toxicity. [22] | Reassess toxidrome, exposure history, and response to treatment. [22] |

## Titrate atropine to a clear chest and add pralidoxime as adjunctive therapy

Antimuscarinic treatment is guided by pulmonary secretions, not a fixed cumulative dose.

For adult nerve-agent or highly toxic organophosphate exposure, administer atropine 2 mg IM or IV and double the dose every 5-10 minutes until the chest is clear on auscultation and heart rate and systolic blood pressure are adequate; the cited guidance specifies targets of heart rate 80 beats/minute and systolic blood pressure 80 mm Hg. After control, continue atropine 1-2 mg/hour by IV infusion, adjusting to recurrent secretions, for up to 24 hours. [22]

For pesticide poisoning, atropine should be titrated to the same clinically meaningful endpoint—resolution of bronchorrhea—rather than using mydriasis as the principal target. One emergency protocol describes an atropine maintenance infusion at 20% of the atropinizing dose per hour, with tapering after stabilization. [3][21]

Use pralidoxime as an acetylcholinesterase-sparing adjunct with atropine. For adult nerve-agent exposure, cited guidance lists an initial pralidoxime chloride dose of 600 mg, 1,200 mg, or 1,800 mg IM/IV according to exposure severity, followed by 10-20 mg/kg in 0.9% saline by IV infusion; continue until atropine has not been required for 12-24 hours. A separate emergency protocol uses 2 g IV in 100 mL normal saline over 30 minutes followed by 1 g IV four times daily. [22][21]

The pralidoxime decision requires clinical judgment because adult trial data have not conclusively established efficacy in acute organophosphate poisoning. Do not withhold atropine or respiratory support while considering oxime therapy, and do not use pralidoxime alone as treatment for acute toxicity. [23][3]
- Escalate atropine whenever bronchial secretions recur; a recurrent wet chest is a treatment failure signal even if pupils remain small. [3][22]
- Continue oxime therapy only in conjunction with ongoing clinical assessment and atropine adjustment; oximes and atropine are complementary components of antidote treatment. [3][16]
- For nerve-agent casualties, antidotal therapy is broadly similar to pesticide toxicity, but exposure-specific operational protocols may govern autoinjector use and decontamination. [22][6]

*Antidotal treatment endpoints and source-described regimens. [3][21][22][23]*

| Therapy | Initial regimen | Titration or continuation | Decision endpoint |
| --- | --- | --- | --- |
| Atropine | 2 mg IM/IV for adult nerve-agent/highly toxic organophosphate exposure. [22] | Double every 5-10 minutes; after control, 1-2 mg/hour IV infusion adjusted as needed for up to 24 hours. [22] | Clear chest; adequate heart rate and systolic blood pressure. [22] |
| Atropine, alternative protocol | 3-5 ampules IV bolus in one emergency protocol. [21] | Increase according to clinical progression; maintenance infusion described as 20% of atropinizing dose per hour. [21] | No crepitations or wheezes and drying of secretions are listed signs of atropinization. [21] |
| Pralidoxime | 600 mg, 1,200 mg, or 1,800 mg IM/IV by severity in adult nerve-agent guidance; another protocol uses 2 g IV over 30 minutes. [22][21] | 10-20 mg/kg IV infusion in 0.9% saline or 1 g IV four times daily in the alternative protocol. [22][21] | Continue nerve-agent regimen until atropine has not been needed for 12-24 hours. [22] |

## Prevent secondary exposure and monitor for recurrent respiratory failure

Disposition is determined by respiratory status, atropine requirement, and neurologic trajectory.

Maintain contamination control during emergency care. Remove clothing and decontaminate skin with soap and water after dermal exposure; this reduces ongoing absorption and limits nosocomial poisoning risk. [22][20]

Consider gastric decontamination only after airway and hemodynamic stabilization. Nasogastric aspiration of liquid poison may be used for high-risk ingestions such as organophosphates, whereas orogastric lavage carries substantial risk with limited evidence of benefit. Activated charcoal may be considered within 1 hour of a potentially toxic ingestion but is contraindicated with an unprotected airway or CNS depression. [3]

Admit patients with ongoing bronchorrhea, respiratory compromise, coma, seizures, or a continuing atropine infusion to an intensive-care setting for ventilatory support and frequent reassessment. Respiratory failure can arise from impaired respiratory pump function and/or direct lung injury in poisoning; monitor serial lung examination, oxygenation, ventilation, mental status, ECG, and recurrent secretion burden. [11][19][21]
- Use emergency observation only after clinical stability, absence of ongoing respiratory compromise, and no need for intensive monitoring or escalating antidote therapy; one emergency protocol separates stable observation from ICU disposition. [21]
- For intentional ingestion, arrange psychiatric assessment after medical stabilization and removal from acute toxicity monitoring. [2]

*Disposition decisions after acute organophosphate exposure. [11][19][21][22]*

| Clinical state | Location | Monitoring or intervention |
| --- | --- | --- |
| Respiratory failure, coma, seizures, or ongoing ventilatory support [19][22] | ICU | Ventilatory support, continuous reassessment of secretions and neurologic status, and adjusted atropine therapy. [19][22] |
| Persistent need for atropine infusion or recurrent bronchorrhea [21][22] | ICU or equivalently monitored critical-care setting | Serial chest examinations and infusion titration to pulmonary endpoint. [3][22] |
| Clinically stable after evaluation [21] | Emergency observation | Continue observation for recurrence and reassess disposition if respiratory, neurologic, or secretory toxicity develops. [21] |

## Manage suspected nerve-agent exposure as a hazardous-materials emergency

Nerve agents are highly toxic organophosphates requiring simultaneous patient care and scene safety.

Nerve agents are organophosphate compounds with substantially greater toxicity than pesticide organophosphates. Move patients to uncontaminated air, remove clothing, decontaminate skin, and coordinate antidote delivery with hazardous-materials procedures to prevent rescuer exposure. [10][22]

Use atropine plus an oxime as first-line pharmacologic treatment for nerve-agent exposure, with supportive treatment for respiratory failure, coma, and seizures. Autoinjector products containing atropine and an oxime may be used under applicable emergency-response protocols. [22][6]

## References
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## Editorial note

Prepared from cited clinical literature using Astra's research workflow. Verify recommendations against current guidance and patient-specific factors.