Residency · Residency · Medicine-Pediatrics
Toxicology Across Ages
Introduction
Poisoning and toxic exposures represent a significant cause of morbidity and mortality across the lifespan. In children, unintentional ingestions predominate, typically in toddlers aged 1-5 years exploring their environment. In adolescents and adults, intentional ingestions (self-harm, substance abuse) and occupational exposures are more common. Med-peds physicians must master the systematic approach to the poisoned patient, recognize toxidromes, and apply age-appropriate decontamination and treatment strategies.
Epidemiology
U.S. poison control centers receive over 2 million calls annually; ~50% involve children under age 6. Most pediatric exposures are single-agent, unintentional, and result in minimal toxicity. Leading causes of pediatric poisoning deaths: opioids, cardiovascular medications, and acetaminophen. Adult poisoning deaths are most commonly from opioids, sedative-hypnotics, and stimulants. The opioid epidemic has dramatically increased poisoning mortality across all age groups.
Approach to the Poisoned Patient
Initial Stabilization
ABCs take priority: secure airway, ensure adequate ventilation, establish IV access. Dextrose (D10W 5 mL/kg in children, D50W 50 mL in adults) for altered mental status with hypoglycemia. Naloxone 0.1 mg/kg (pediatric, max 2 mg) or 0.4-2 mg IV (adult) for suspected opioid toxicity; titrate to respiratory effort. Flumazenil: Generally avoided due to seizure risk in chronic benzodiazepine users or mixed ingestions. Continuous cardiac monitoring and 12-lead ECG for all significant ingestions.
Toxidrome Recognition
| Toxidrome | Vital Signs | Pupils | Key Features | Common Causes |
|---|---|---|---|---|
| Sympathomimetic | Tachy, HTN, hyperthermia | Mydriasis | Diaphoresis, agitation | Cocaine, amphetamines |
| Anticholinergic | Tachy, HTN, hyperthermia | Mydriasis | Dry skin, urinary retention, delirium | TCAs, antihistamines, jimsonweed |
| Cholinergic | Brady, hypotension | Miosis | SLUDGE/BBB (salivation, lacrimation, bronchospasm) | Organophosphates, carbamates |
| Opioid | Brady, hypotension, bradypnea | Miosis | Respiratory depression, decreased AMS | Morphine, fentanyl, methadone |
| Serotonin syndrome | Tachy, HTN, hyperthermia | Mydriasis | Clonus, hyperreflexia, agitation | SSRIs + MAOIs, tramadol |
Sympathomimetic: Tachycardia, hypertension, hyperthermia, mydriasis, diaphoresis (cocaine, amphetamines) Anticholinergic: "Hot as a hare, dry as a bone, red as a beet, mad as a hatter, blind as a bat" (antihistamines, TCAs, jimsonweed) Cholinergic: SLUDGE/BBB - Salivation, Lacrimation, Urination, Defecation, GI distress, Emesis, Bradycardia, Bronchospasm, Bronchorrhea (organophosphates, carbamates) Opioid: Miosis, respiratory depression, decreased mental status. Serotonin syndrome: Clonus, hyperreflexia, hyperthermia, agitation (SSRIs, MAOIs, tramadol combinations)
"One-Pill Killers" in Pediatrics
Certain medications can cause life-threatening toxicity in toddlers from a single pill or small dose:
Calcium channel blockers: Hypotension, bradycardia, hyperglycemia; treat with high-dose insulin-euglycemia therapy, calcium, vasopressors. Sulfonylureas: Profound hypoglycemia lasting 12-24 hours; requires prolonged glucose monitoring and octreotide. Opioids (methadone, buprenorphine): Respiratory depression; extended observation needed for long-acting formulations. Tricyclic antidepressants: Seizures, wide QRS, arrhythmias; sodium bicarbonate for QRS >100 ms. Beta-blockers: Bradycardia, hypotension, hypoglycemia; glucagon is the specific antidote. Clonidine: Altered mental status, bradycardia, respiratory depression, miosis mimicking opioid toxicity.
Specific Toxicologic Emergencies
Acetaminophen
Most common cause of acute liver failure in the U.S. and UK. Toxic dose: >150 mg/kg in children; >7.5 g in adults (or >150 mg/kg) Rumack-Matthew nomogram: Plot 4-hour serum level to guide treatment (only valid for acute single ingestions) N-acetylcysteine (NAC): Antidote; most effective within 8 hours but beneficial up to 24+ hours; IV protocol preferred for fulminant cases.
Salicylates
Causes mixed respiratory alkalosis and metabolic acidosis. Tinnitus, hyperpnea, altered mental status, hyperthermia. Treatment: IV sodium bicarbonate for urine alkalinization (target urine pH 7.5-8.0), dextrose supplementation, hemodialysis for severe cases (level >90 mg/dL, end-organ dysfunction, refractory acidosis)
Iron
Particularly dangerous in pediatric ingestions; elemental iron >60 mg/kg is potentially lethal. Phases: GI toxicity (0-6 hr), latent period (6-24 hr), systemic toxicity and shock (12-48 hr), hepatotoxicity (48-96 hr) Deferoxamine chelation for symptomatic patients with serum iron >500 mcg/dL or metabolic acidosis.
Carbon Monoxide
Headache, nausea, confusion progressing to coma and death. Carboxyhemoglobin (COHb) levels guide severity; pulse oximetry is unreliable. Treatment: 100% oxygen via non-rebreather; hyperbaric oxygen considered for COHb >25%, loss of consciousness, or pregnancy.
Decontamination
Activated charcoal: Most effective within 1-2 hours of ingestion; dose 1 g/kg (max 50 g); contraindicated if unprotected airway, caustic ingestion, or hydrocarbons. Whole bowel irrigation: For sustained-release preparations, iron, lithium, and body-packing; polyethylene glycol solution at 500 mL/hr (children) or 1-2 L/hr (adults) Gastric lavage: Rarely indicated; considered only for life-threatening ingestions within 1 hour. Syrup of ipecac: No longer recommended in any setting.
Substance Use Considerations
Adolescents: Screen for intentional ingestions; psychiatric evaluation mandatory for all intentional overdoses. Adults: Consider polypharmacy, illicit substances, and alcohol co-ingestion. Fentanyl: Increasing presence in counterfeit pills and illicit drug supply; ultra-potent requiring higher and repeated naloxone doses. Vaping-related illness: EVALI presents with respiratory distress, bilateral infiltrates; often vitamin E acetate exposure.
Clinical Pearls
In toddlers, even a single pill of a calcium channel blocker, sulfonylurea, or opioid can be fatal; these require mandatory observation. Acetaminophen levels should be obtained in all intentional ingestions regardless of reported substances taken. The Rumack-Matthew nomogram is only valid for acute single-time ingestions of immediate-release acetaminophen. Activated charcoal is most effective within one hour but should not delay definitive antidote administration. All intentional overdoses in adolescents and adults require psychiatric evaluation before discharge.
References
- Gummin DD, Mowry JB, Beuhler MC, et al. 2022 Annual Report of the National Poison Data System. Clin Toxicol. 2023;61(12):1-88.
- Hendrickson RG, McKeown NJ. Acetaminophen. In: Nelson LS, et al., eds. Goldfrank's Toxicologic Emergencies. 11th ed. McGraw-Hill; 2019.
- Beauchamp GA, Hendrickson RG. The one-pill killers: A review of the toxic medications that can cause death in toddlers. Pediatr Emerg Med Rep. 2020;25(1):1-12.
- Mowry JB, Spyker DA, Brooks DE, et al. Annual Report of the American Association of Poison Control Centers. Clin Toxicol. 2016;54(10):924-1109.
For the intern
At 3am, focus on ABCs, stabilization, and antidote administration. Secure the airway if altered mental status threatens it. Give naloxone for suspected opioid toxicity, dextrose for hypoglycemia, and start high-dose insulin-euglycemia therapy for calcium channel blocker poisoning immediately. Order STAT acetaminophen and salicylate levels on any intentional ingestion regardless of history—patients often underreport or don't know what they took. Start N-acetylcysteine if acetaminophen toxicity is suspected; don't wait for levels if presentation is delayed beyond 8 hours. Activated charcoal can usually wait until morning if the patient is stable and beyond the 1-2 hour window, but NAC, sodium bicarbonate for salicylates or wide-QRS from tricyclics, and deferoxamine for iron cannot wait. Poison control (1-800-222-1222) is your best friend at 3am—call early and often.
Common pitfalls
- Trusting pulse oximetry in carbon monoxide poisoning—it reads falsely normal because carboxyhemoglobin is interpreted as oxyhemoglobin. Always order co-oximetry.
- Using the Rumack-Matthew nomogram for chronic acetaminophen ingestions—it's only valid for acute single ingestions. Treat empirically if chronic overdose or unknown timing.
- Giving flumazenil for "presumed benzodiazepine overdose"—this can precipitate seizures in chronic users or mixed ingestions with seizurogenic substances.
- Discharging a toddler too early after "one-pill killer" exposure—sulfonylureas cause delayed hypoglycemia up to 24 hours; extended-release formulations have delayed toxicity.