What is the treatment for insecticide poisoning?

Treatment of Insecticide Poisoning

The treatment of insecticide poisoning depends critically on the specific class of insecticide involved, with organophosphate poisoning requiring immediate atropine administration (and potentially pralidoxime), while most other insecticide exposures require primarily supportive care and decontamination. 1, 2

Immediate Assessment and Stabilization

Contact poison control immediately (1-800-222-1222 in the US) while initiating treatment for any patient with signs of life-threatening poisoning including altered mental status, seizures, difficulty breathing, or vomiting. 3

Critical Initial Steps:

• Ensure your own safety first—do not contaminate yourself during decontamination 3, 2
• Remove all contaminated clothing and jewelry immediately 4
• Assess airway, breathing, and circulation—intubate early if respiratory failure is developing 5
• Identify the specific insecticide class from the product label or container 3, 2

Decontamination (All Insecticide Types)

Dermal Exposure:

• Brush off any powdered chemicals with a gloved hand before washing 3
• Wash skin thoroughly with large volumes of water, soap, and shampoo as soon as possible 1, 2
• For organophosphate exposure specifically, use sodium bicarbonate or alcohol for washing 1

Eye Exposure:

• Irrigate eyes immediately with copious amounts of water for at least 15 minutes 3, 4

Ingestion (if within 60 minutes):

• Perform gastric lavage if presentation is within 60 minutes of ingestion 1, 2
• Administer activated charcoal (1 g/kg) combined with a cathartic within 60 minutes of ingestion 2
• Do NOT induce vomiting with syrup of ipecac—this is contraindicated 3, 2
• Do NOT administer anything by mouth unless specifically directed by poison control 3, 4

Organophosphate/Carbamate Insecticide Poisoning

This is the most dangerous class requiring specific antidotal therapy. The clinical presentation is characterized by the cholinergic syndrome ("all faucets on"): miosis, excessive salivation, lacrimation, urination, defecation, bronchorrhea, bronchospasm, and muscle fasciculations. 5, 2

Atropine Administration (FIRST-LINE TREATMENT):

Atropine is the drug of choice and must be given as soon as possible after correcting hypoxemia—do NOT give atropine in the presence of significant hypoxia due to risk of ventricular fibrillation. 1

Adult Dosing:

• Initial dose: 2-4 mg IV, repeated every 5-10 minutes until full atropinization (secretions inhibited) or atropine toxicity appears (delirium, hyperthermia, muscle twitching) 1
• Maintain some degree of atropinization for at least 48-72 hours until blood cholinesterase activity reverses 1

Pediatric Dosing:

• Children require substantially higher doses: up to 0.1 mg/kg, which is much higher than typical pediatric resuscitation doses 6
• Do NOT stop atropine in the presence of tachycardia in children—repeated boluses do not cause cardiac arrhythmias in this population, unlike adults 6

Pralidoxime (Oxime) Therapy—CONTROVERSIAL:

The role of pralidoxime remains highly controversial with conflicting evidence. The FDA label recommends its use 1, but high-quality randomized controlled trials have failed to demonstrate benefit and some suggest potential harm 7, 8.

FDA-Approved Regimen (if used):

• Initial dose: 1-2 g IV infusion over 15-30 minutes in 100 mL normal saline 1
• Maintenance: May repeat every 3-8 hours or use continuous infusion of 500 mg/hour 1
• Must be given within 36 hours of exposure for any potential benefit 1
• Continue dosing as long as signs of poisoning recur—"titrate" the patient 1

Critical Limitations:

• A 2009 randomized controlled trial of 235 patients found pralidoxime produced substantial red cell acetylcholinesterase reactivation but showed NO survival benefit and a nonsignificant trend toward increased mortality (24.8% vs 15.8%, HR 1.69) 8
• Most severe poisonings now involve less potent WHO class Ib/II insecticides with large volume ingestions, not the highly potent parathion for which pralidoxime was originally developed 7
• Pralidoxime is NOT effective for carbamate poisoning and may increase toxicity of carbaryl specifically 1

Given the conflicting evidence, if pralidoxime is used, it should be combined with aggressive atropine therapy and supportive care, not used as monotherapy. 1, 5

Respiratory Management:

Respiratory failure is the leading cause of death in organophosphate poisoning—early recognition and intubation is life-saving. 5

• Intubate for: respiratory failure, depressed consciousness with inability to protect airway, hemodynamic instability, or increasing respiratory rate (e.g., 22 to 38 breaths/min indicates impending failure) 5
• Mortality is 50% in patients requiring mechanical ventilation vs 21.6% in those not ventilated 5
• Avoid succinylcholine—prolonged paralysis occurs with anticholinesterase activity present 1

Intermediate Syndrome:

Watch for intermediate syndrome occurring in 19% of patients at 24-96 hours after initial cholinergic crisis, characterized by respiratory muscle weakness. 6

• This syndrome is associated with delayed intubation and increased mortality 6
• Maintain close monitoring for at least 48-72 hours, longer if ongoing absorption from gastrointestinal tract 1

Seizure Management (Pediatric):

Convulsions occur more frequently in children due to rapid hypoxia development from respiratory muscle weakness. 6

• Treat with diazepam 0.2 mg/kg or midazolam 0.1 mg/kg, repeated until complete cessation 6

Medications to AVOID:

• Do NOT use morphine, theophylline, aminophylline, reserpine, or phenothiazine-type tranquilizers 1

Organochlorine Insecticides (Lindane, DDT)

• Primary concern is seizures with excessive use or application to large areas of nonintact skin 2
• Treatment is supportive with benzodiazepines for seizure control 2
• No specific antidote exists 2

Pyrethrin/Pyrethroid Insecticides

• These rarely produce more than mild skin, eye, or gastrointestinal irritation 2
• Treatment is symptomatic with decontamination 2

Herbicides (Non-Dipyridyl)

• Most produce only mild irritation 2
• Chlorate salt-containing herbicides can be particularly dangerous 9
• Treatment is primarily supportive 2

Monitoring and Disposition

• All organophosphate-poisoned patients require observation for at least 48-72 hours due to risk of relapse from continued gastrointestinal absorption 1
• Monitor for complications: aspiration pneumonia (most common), urinary tract infections, septic shock 5
• Average ICU stay for severe poisoning is 5.2 ± 3.0 days 5