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Poisonous animals
Cnidarians (Jellyfish, Corals and Anemones)
Venomous fish
Hymenopterans (Bees, Wasps and Ants)
Sea snakes
Terrestrial snakes
Miscellaneous animals
North America
Mexico and Central America
South America and the West Indies
North Africa, Near and Middle East
Central and Southern Africa
The Far East
Indian Subcontinent and Southeast Asia
Australia and the Pacific Islands

Is the patient envenomed?


Is it likely that a clinically relevant injection of venom has taken place?

D  Diagnostics


  • time of the bite,
  • local pain,
  • nausea, vomiting, diarrhoea, abdominal pain,
  • retrosternal pain.


  • state of consciousness.


  • blood pressure/pulse,
  • respiratory rate.


  • bite marks,
  • extent and intensity of the swelling,
  • bleeding in the region of the swelling (ecchymoses),
  • enlargement and painfulness of regional lymph nodes,
  • swelling in the facial region, including the larynx/pharynx (angio-oedema),
  • bronchospasm,
  • clinical signs of shock,
  • signs of systemic bleeding (very rare),
  • signs of paralysis (very rare).


  • venom concentration in the serum/urine using the ELISA method (clinically proven and standardised tests are not yet commercially available), 
  • clotting time (bedside test),
  • urinary output.
C  Comments

The symptoms and degree of envenoming depend not only on the amount of venom injected and numerous other variables, but also on the time that has elapsed since the bite. This variable factor must be taken into account when making the following decisions:

  • exclusion of envenoming (see below),
  • the time interval between clinical examinations (see Therapy phase: Hospital),
  • emergency care.

The following signs and symptoms are observed following European viper bites and are indicative of a relevant injection of venom:

  • local pain, swelling and skin changes (in particular ecchymoses),
  • nausea, vomiting, diarrhoea, abdominal pain,
  • arterial hypotension,
  • signs of shock (pallor, sweating, tachycardia, arterial hypotension, alterations in consciousness).
  • neurological signs and symptoms, in particular cranial nerve deficits (rare and only in certain geographical areas).

The severity of envenoming at the time of investigation can be estimated from the constellation of signs and symptoms found (see Table 4.12).

ELISA tests are not yet commercially available. However, they are a promising method that will have a high predictive value for the expected severity of envenoming as soon as they are clinically proven and standardised (see Table 4.12).

Exclusion of a relevant injection of venom

D  Diagnostics


No swelling/oedema in the region of the bite within 2 h and no signs or symptoms apart from those that can be attributed to the psychological trauma of a snakebite.

C  Comments

The relationship between swelling oedema at the site of the bite and systemic envenoming was investigated in a prospective study by Audebert et al. (1992). With regard to systemic envenoming, swelling / oedema at the bite site had a sensitivity of 100%, a specificity of 85%, a positive predictive value of 65% and a negative predictive value of 100%. In this study it was also found that in all patients who developed swelling /oedema at the site of the bite, it commenced within the first 2 h.