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For further information, see CMDT Part 38-55: Snake Bites

Key Features

  • Venom may be neurotoxic (coral snake) or cytolytic (rattlesnakes, other pit vipers)

  • Neurotoxins cause respiratory paralysis; cytolytic venoms cause tissue destruction by digestion and hemorrhage due to hemolysis and destruction of the endothelial lining of the blood vessels

Clinical Findings

  • Manifestations of rattlesnake envenomation

    • Local pain

    • Redness

    • Swelling

    • Extravasation of blood

  • Other manifestations

    • Perioral tingling

    • Metallic taste

    • Nausea

    • Vomiting

    • Hypotension

    • Ptosis

    • Dysphagia

    • Diplopia

    • Respiratory arrest

  • Coagulopathy common and includes prolonged PT and thrombocytopenia (sometimes severe)


  • Immobilize patient and bitten area in neutral position

  • Avoid manipulation of area

  • Do not apply ice or tourniquet

  • Do not give stimulants

  • Incision and suction of bite by unskilled persons probably not useful

  • Transport patient to medical facility

Pit viper (eg, rattlesnake) envenomation

  • There are two commercially available antivenins for rattlesnake envenomation (CroFab and Anavip)

  • CroFab

    • Administered in increments of 4–6 vials in 250–500 mL saline by slow intravenous drip depending on the severity of symptoms

    • Higher doses and additional vials may be required for more serious envenomation with marked local effects and systemic toxicity (eg, hypotension, coagulopathy),

  • Anavip

    • Dosage: 10 vials by slow intravenous infusion over 60 minutes initially, followed by additional 10 vial increments as needed for more serious envenomations or for progression of symptoms

    • Monitor vital signs and the blood coagulation profile

    • Type and cross-match blood

  • Adequacy of venom neutralization indicated by improvement in symptoms and signs and slowed swelling rate

  • Prophylactic antibiotics not indicated

Elapid (coral snake) envenomation

  • 1–2 vials of specific antivenom as soon as possible

  • Antivenom no longer made in United States; supplies are dwindling

  • Call regional poison control center (1-800-222-1222) to locate antisera

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