Venom effects

North American Pit Viper Envenomation

Venom effects

North American pit viper venom contains a complex mixture of toxins that often includes*:

  • Procoagulants
  • Anticoagulants
  • Cardiocoagulants
  • Hemotoxins
  • Necrotoxins
  • Neurotoxins

Each toxin may have distinct actions on diverse body systems, and different toxins may work synergistically to increase toxicity.

  • Effects can range from no apparent clinical effects or local effects at the bite site to life-threatening effects that can affect every major organ in the body
  • Effects may begin within minutes or be delayed for hours, with the more severe effects not becoming evident for many hours
  • Locally active toxins may show clinical effects almost immediately Systemically active toxins must first reach the bloodstream, where they will rapidly exert their effect
  • Toxins with extravascular targets, such as neurotoxins and myotoxins, generally have a more delayed onset
  • Rapidity of effect can also be influenced by any latency period between time of binding to the target tissue and onset of detectable activity

After envenomation, a depot of venom often remains at the site of the bite, which may prolong the clinical effects of the venom.

  • Following intramuscular injection of venom in animal models, absorption of venom has been shown to last for 72 hours.

*Venom toxins vary from species to species.

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