Rattlesnake Envenomation Clinical Presentation

Updated: Jun 25, 2015
  • Author: Sean P Bush, MD, FACEP; Chief Editor: Joe Alcock, MD, MS  more...
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All or none of the following may be present. Note that symptoms are subject to change, and this change can be very rapid or very insidious. In addition, severity is generally guided by the most severely affected parameter. [4, 5, 6, 7, 8] See the following:

  • Pain around the bite site
  • Swelling
  • Taste changes (eg, a metallic taste)
  • Difficulty breathing
  • Chest pain
  • Nausea, vomiting, or diarrhea
  • Hematemesis, hematochezia
  • Neurologic symptoms - Weakness, paresthesias
  • Syncope, near syncope


Physical examination findings may include the following:

  • Fang marks - May be 1, 2, or more, or may be unable to discern (See the image below.)
    Moderate rattlesnake envenomation in a toddler aft Moderate rattlesnake envenomation in a toddler after treatment with antivenom. Photo by Sean Bush, MD.
  • Tenderness surrounding the bite site
  • Local edema: Use a pen to mark and time the border of advancing edema every 15-20 minutes initially. Once stabilization with antivenom has occurred, repeat measurements every 1-2 hours. Rapidly progressive swelling is usually indicative of a severe envenomation.
  • Erythema
  • Ecchymosis
  • Bullae
  • Bleeding
  • Hypotension/hypertension
  • Tachycardia
  • Myokymia (muscle fasciculations)
  • Neurologic effects
  • Lethargy


A large percentage of bites occur when a snake is handled, kept as a pet, or abused. These are considered intentionally interactive bites. Many bites are associated with ethanol use.