Toxin

Poison Hemlock

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Poison Hemlock, Hemlock Toxicity, Hemlock Poisoning, Hemlock Ingestion, Conium Maculatum, Conium Maculatum Poisoning, Coniine

  • Background
  1. Poison Hemlock is a group of Poisonous Plants in the cicuta or conium genus
    1. Unrelated to the coniferous hemlock tree (which is not poisonous)
    2. Historically, Socrates was poisoned with hemlock
  2. Poison Hemlock (Conium Maculatum) may be found as a non-native weed throughout the U.S.
    1. White flowers and hollow stem
    2. Growth height up to 5 feet
    3. Similar appearance to wild carrot or wild celery
    4. All parts of hemlock plant are poisonous
  • Mechanism
  • Toxicity
  1. Hemlocks contain a group of nicotinic, piperidine alkaloids including Coniine, which act at Nicotinic Acetylcholine Receptors
  2. Early, alkaloids are Agonists at Nicotinic Acetylcholine Receptors
  3. Later, alkaloids are antagoinsts at Nicotinic Acetylcholine Receptors (resulting in paralysis)
  • Pharmacokinetics
  1. Coniine is rapidly absorbed after ingestion
  2. Toxic ingestion level (6 to 8 leaves): >150 mg Coniine
  • Signs
  1. Ocular (early)
    1. Blurred Vision
    2. Mydriasis
  2. Lung
    1. Early: Bronchoconstriction and bronchorrhea
    2. Later: Respiratory paralysis
  3. Cardiac
    1. Early: Tachycardia and Hypotension
    2. Later: Bradycardia
  4. Gastrointestinal (early)
    1. Salivation
    2. Nausea and Vomiting
  5. Neurologic (later)
    1. Ascending flaccid Muscle paralysis
    2. CNS Depression
    3. Seizures
    4. Myalgias
    5. Rhabdomyolysis
  • Labs
  1. See Unknown Ingestion
  2. Basic chemistry panel (chem8)
  3. Creatine Phosphokinase (CPK)
  4. Coniine
    1. Although serum and urine levels may be obtained, they are not typically useful in clinical decision making
  • Management
  1. ABC Management
    1. Advanced Airway and Mechanical Ventilation may be needed
  2. Supportive Care
    1. Antiemetics
    2. Intravenous Fluids
  3. Seizures
    1. Benzodiazepines
  4. Hemodynamic instability and Hypotension
    1. Vasopressors as needed if refractory to Intravenous Fluids
  5. Rhabdomyolysis
    1. See Rhabdomyolysis
    2. Hemodialysis is not effective
  6. Disposition
    1. Improving or asymptomatic patients may be discharged at 6 hours after ingestion
  • Complications
  1. Respiratory Failure (may be lethal without intervention)
  2. Rhabdomyolysis
  • References
  1. Tomaszewski (2023) Crit Dec Emerg Med 37(9): 32
  2. Vetter (2004) Food Chem Toxicol 42(9):1373-82 +PMID: 15234067 [PubMed]
  3. Konca (2016) Turk J Emerg Med 14(1):34-6 +PMID: 27331163 [PubMed]