Envenoming: Consequences and Management


Some snakes, lizards, arthropods and aquatic animals can inject venom into prey or enemies by biting or stinging. These accidents are preventable by wearing boots, using a light after dark and not sleeping unprotected on the ground. Treatment involves specific antivenom, supporting vital functions and surgically debriding necrotic wounds.

Snakebites: Local effects include swelling, blistering, necrosis and painful lymph node enlargement. Life‐threatening systemic effects are shock, bleeding, descending paralysis, generalised rhabdomyolysis, intravascular haemolysis and acute kidney injury.

Arthropods: Hypersensitisation to bee, wasp and ant venoms is a common cause of fatal anaphylaxis. Mass attacks can kill unsensitized people. Scorpion stings are intensely painful and may cause autonomic storm, leading to myocardial damage and pulmonary oedema particularly lethal in children. Some species cause neurotoxic effects. Loxosceles spiders cause local necrosis while Latrodectus bites cause painful muscle spasms.

Fish, cnidarian (jellyfish), coral, cone shell and sea urchin stings can be painful and dangerous.

Key Concepts

  • Animal venoms and venom apparatus have evolved to immobilise and digest their prey, and for defence.
  • Knowledge of the venomous fauna of a particular locality, use of protective footwear, a flash light after dark and avoidance of sleeping on open ground reduce the risk of envenoming.
  • Antivenom, purified immunoglobulin from animals that have been hyperimmunised with specific venoms, is the only antidote to envenoming.
  • Animal venoms may have tissue‐damaging local effects leading to permanent dysfunction and, by targeting physiological receptors, can cause haemostatic disturbances, shock, paralysis and autonomic nervous system overactivity.
  • Snakebite is a neglected occupational and environmental disease particularly affecting agricultural workers and their children in tropical developing countries. Community education is of paramount importance in reducing risky behaviour.
  • The greatest risk after neurotoxic snakebite is respiratory arrest. This may be delayed by first‐aid pressure immobilisation and treated by assisted ventilation.
  • Identification of the biting species, either directly if the causative animal, or a photographic image of it, is available, or by use of clinical syndrome‐based algorithms, is important for optimal management.
  • Bee, wasp and ant stings more often kill by anaphylaxis in hypersensitized people than by direct effects of their venoms.

Keywords: venoms; poisons; bites; stings; antivenom; treatment

Figure 1. Fangs of a South American pit viper (Jararacuçu from Brazil, Bothrops jararacussu) showing erected fangs, one emitting a drop of venom. Copyright © DA Warrell.
Figure 2. Severe local effects of envenoming. Swelling, bruising and blistering of the lower limb of a boy bitten by a Malayan pit viper (Calloselasma rhodostoma) 4 days earlier. Copyright © DA Warrell.
Figure 3. Spontaneous systemic bleeding of the gums and floor of the mouth in a patient bitten by a saw‐scaled viper in Nigeria (Echis ocellatus). Copyright © DA Warrell.
Figure 4. Neurotoxic envenoming in a woman bitten by a common krait (Bungarus caeruleus) in Sri Lanka. Note paralysis of the eyelids (ptosis). She is struggling to open her mouth and protrude her tongue. Copyright © DA Warrell.
Figure 5. Pressure‐pad plus immobilisation technique.
Figure 6. Transfer of a boy with advanced cobra‐bite paralysis to medical care by a village‐based volunteer motorcycle driver in Nepal. Copyright SK Sharma.
Figure 7. Swelling rapidly advancing up the arm in a man bitten by a saw‐scaled viper (Echis ocellatus) in Nigeria. Copyright © DA Warrell.
Figure 8. Dangerous Brazilian scorpion (Tityus obscurus). Note slender pincers (pedipalps) implying a potent venom (see text). Copyright © DA Warrell.


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Warrell, David A(Oct 2015) Envenoming: Consequences and Management. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0002188.pub3]