What are the signs of hemlock poisoning?

Signs and Symptoms of Hemlock Poisoning

Hemlock poisoning is a medical emergency characterized by progressive neuromuscular symptoms that can rapidly lead to respiratory failure and death if not promptly recognized and treated.

Initial Presentation

• Early symptoms (30 minutes to 3 hours after ingestion):
  • Burning sensation in mouth
  • Hypersalivation
  • Nausea and vomiting
  • Diarrhea
  • Tremor in hands 1

Neurological Manifestations

• Central nervous system effects:
  • Ataxia (unsteady gait) 1
  • Tremors progressing to muscle weakness
  • Dizziness and confusion
  • Seizures in severe cases 2
  • Delirium or altered mental status 3

Neuromuscular Progression

• Ascending paralysis pattern:
  • Initial muscle weakness in extremities
  • Progressive paralysis moving upward
  • Respiratory muscle involvement (critical sign) 4
  • Rhabdomyolysis (muscle breakdown) 5, 2

Cardiovascular Signs

• Tachycardia (early phase)
• Bradycardia (later phase)
• Hypotension
• Cardiac dysrhythmias
• Potential cardiac arrest in severe cases 3

Respiratory Manifestations

• Progressive respiratory compromise:
  • Shortness of breath
  • Respiratory depression
  • Respiratory failure (primary cause of death) 5, 4

Laboratory Findings

• Elevated creatine kinase (indicating muscle damage)
• Metabolic acidosis
• Potential acute renal failure secondary to rhabdomyolysis 2
• Electrolyte imbalances 5

Time Course

• Symptoms typically begin within 30-60 minutes of ingestion
• Severe toxicity can develop within 1-2 hours
• Death from respiratory failure can occur within 2-3 hours in untreated severe cases 6
• If the patient survives the acute phase, recovery typically occurs within a few days 4

High-Risk Indicators

• Rapid onset of symptoms
• Progression of muscle weakness to involve respiratory muscles
• Altered mental status
• Seizures
• Cardiovascular instability 5

Special Considerations

• Children may develop symptoms more rapidly due to lower body mass 1
• Intravenous exposure (extremely rare) can cause prolonged weakness and encephalopathy 3
• Hemlock poisoning can be mistaken for other conditions due to its nicotinic syndrome presentation (initial excitatory phase followed by inhibitory phase) 6

Important Pitfalls to Avoid

• Failing to recognize the ascending paralysis pattern as characteristic of hemlock poisoning
• Delaying respiratory support when signs of respiratory compromise appear
• Underestimating the rapidity of progression from mild symptoms to life-threatening respiratory failure 5
• Misidentifying the plant as edible species (celery, parsnip, carrots) 6

Prompt recognition of these signs and immediate medical attention are essential, as respiratory support is the cornerstone of management for hemlock poisoning.