This topic covers the principles behind every poisoning, whatever the substance.

Basic toxicology

• Dose–response: any substance can be toxic at a high enough dose. Toxicity depends on the amount, duration, route, and the client's ability to metabolize and excrete it (age, liver and kidney function, genetics, other drugs).
• Therapeutic index: the gap between the effective and the toxic dose. Narrow-index drugs (digoxin, lithium, warfarin, phenytoin, theophylline, aminoglycosides) cause toxicity with small changes in dose or clearance.
• Acute toxicity follows a single or short exposure and appears quickly. Chronic toxicity builds up with repeated exposure (e.g., chronic lithium or digoxin toxicity) and can be severe at lower serum levels.
• Target organs: liver (acetaminophen, methotrexate), kidney (aminoglycosides, lithium, toxic alcohols), bone marrow (methotrexate, chemotherapy), heart (anthracyclines, digoxin, tricyclic antidepressants), nervous system (organophosphates, sedatives).
• Extended-release products and co-ingestions can cause delayed or prolonged toxicity; a well-looking client early on is not proof of safety.

The management sequence

1. Stabilize — airway, breathing, circulation, disability (glucose), exposure (temperature)
2. Assess — history, toxidrome, focused tests
3. Decontaminate when the benefit outweighs the risk
4. Specific antidote if one exists and is indicated
5. Enhance elimination in selected poisonings
6. Supportive care, observation, and disposition (including mental health evaluation after intentional ingestion)

Most poisoned clients recover with good supportive care alone; antidotes exist for only a few poisons.

Toxidromes — pattern recognition guides early treatment

Decontamination and elimination tools

Substances activated charcoal does not bind well: metals (iron, lithium, lead), alcohols (ethanol, methanol, ethylene glycol), acids and alkalis, and most hydrocarbons.

• Activated charcoal is contraindicated with an unprotected airway (drowsy, seizing, or likely to deteriorate) unless the client is intubated; caustic ingestion (blocks endoscopy, no benefit); hydrocarbons (aspiration risk); bowel obstruction or perforation.
• Never induce vomiting — especially with caustics (second burn on the way up) and hydrocarbons such as kerosene or gasoline (aspiration pneumonitis).
• Do not "neutralize" acids with bases or bases with acids — the heat of the reaction worsens injury.
• Oral acetylcysteine given near charcoal may be partly bound; IV acetylcysteine avoids the problem.
• Urine drug screens have limits: many standard opiate immunoassays do not detect fentanyl or other synthetic opioids, and some drugs cause false positives. Treat the client, not the screen.
• Pregnancy: treat the mother fully; most antidotes are given when indicated because maternal survival protects the fetus.
• Children: several adult medicines (e.g., tricyclic antidepressants, calcium channel blockers, sulfonylureas, opioids including buprenorphine, clonidine) can be dangerous to a toddler in a single tablet — observe after any such exposure.

Listed in priority order.

1. Airway, breathing, circulation — open and protect the airway; oxygen; ventilate with a bag-valve mask for inadequate breathing; IV access; continuous cardiac monitoring. Check point-of-care glucose in every client with altered consciousness. Opioid toxidrome → naloxone.
2. Safety — seizure precautions; fall and aspiration prevention (side-lying if vomiting); staff PPE and decontamination for chemical or pesticide exposure before the client enters the treatment area when possible; suicide precautions for intentional ingestion (one-to-one observation, remove means).
3. Exposure history — substance, amount, time of ingestion, route, formulation (extended-release?), co-ingestants including alcohol, intent. Bring containers, pill bottles, and prescription lists; ask family and emergency responders.
4. Focused tests
   • 12-lead ECG — QRS widening (sodium channel blockers such as tricyclic antidepressants), QTc prolongation, bradycardia, heart block
   • Acetaminophen and salicylate levels in every intentional ingestion (both are common and early symptoms may be absent)
   • Electrolytes, anion gap and osmolal gap (toxic alcohols), ABG, glucose, creatinine, liver tests, CK, pregnancy test; specific drug levels (digoxin, lithium, iron, anticonvulsants, carbon monoxide)
5. Decontamination and antidotes as ordered; document times precisely
6. Ongoing monitoring — vital signs, level of consciousness, temperature, urine output; repeat levels and ECG for extended-release products and rising levels
7. Consult the poison center or toxicologist early for dosing, observation time, and disposition
8. Psychosocial care — nonjudgmental approach; psychiatric evaluation once medically stable after self-harm

• Store medicines and chemicals locked, up high, in original child-resistant containers; never store chemicals in drink bottles
• Do not call medicine "candy"; take medicines out of children's sight
• Keep a current medication list; count acetaminophen in combination products
• Dispose of unused medicines through take-back programs or as local guidance directs
• If a poisoning happens: check breathing, call emergency services or the poison center, bring the container; do not induce vomiting or give anything by mouth unless advised
• Families of clients at risk of overdose: learn the signs and keep naloxone available where it is sold or supplied
• Pesticide users: wear gloves and protective clothing, mix and spray downwind, wash after use, store pesticides away from food and out of reach

Common poison–antidote pairs (details in the next three topics)

• ABCs and glucose first — supportive care saves most poisoned clients
• Opioid toxidrome = respiratory depression + miosis + coma → naloxone
• Cholinergic = bradycardia, bronchorrhea, bronchospasm, SLUDGE → atropine (+ pralidoxime for organophosphates)
• Anticholinergic = hot, dry, red, blind, mad, full; sympathomimetic looks similar but the skin is sweaty
• Never induce vomiting; ipecac is not recommended
• Activated charcoal 1 g/kg within about 1 hour, only with a protected airway; does not bind iron, lithium, alcohols, acids and alkalis, hydrocarbons
• Whole-bowel irrigation: iron, lithium, sustained-release drugs, packets
• Check acetaminophen and salicylate levels in every intentional overdose; get an ECG
• Hemodialysis: toxic alcohols, lithium, salicylates
• Narrow therapeutic index drugs cause toxicity with small changes; chronic toxicity can occur at lower levels
• Call the poison center early