Choosing which antivenom to administer

When choosing which antivenom(s) to use (if indicated), it is more important to cover the likely snake group(s) responsible for the bite than to determine the exact snake. Determining the likely snake group(s) is based on knowledge of the local snake fauna and envenoming syndromes typical for those snake group(s) (see Envenoming syndromes and geographical distributions of clinically important Australian terrestrial snakes).

Antivenoms can be categorised as either:

  • monovalent—contains predominantly antibodies to one snake group; examples include tiger snake antivenom and brown snake antivenom
  • polyvalent—contains antibodies to five snake groups—black snake, taipan, death adder, tiger snake and brown snake. This covers most of the clinically important snake groups in Australia and Papua New Guinea.

Monovalent antivenoms are preferred because they have a lower volume per vial and therefore a lower risk of hypersensitivity reactions. The following recommendations are based on the large number of cases studied in the Australian Snake Bite project1 and represent the consensus view of the Toxicology and Toxinology Expert Group.

In most cases of unidentified snake bite, one vial each of monovalent tiger snake antivenom and monovalent brown snake antivenom (ie two vials of antivenom in total) are recommended to ensure adequate coverage of likely snake groups. In addition to covering tiger snake and brown snake envenomings, this will also cover red-bellied black snake envenoming and all snake groups that cause venom-induced consumption coagulopathy (VICC), except taipan envenoming. Although one vial of monovalent snake antivenom contains enough antibodies to neutralise almost all snake envenoming, this two-vial approach provides more than sufficient antibodies to neutralise the venom.

A single vial of monovalent tiger snake antivenom may be sufficient in the following scenarios based on discussion with a clinical toxicologist or a poisons information centre:

  • definite red-bellied black snake bite, based on location and clear identification
  • any snake bite in Tasmania
  • if there is expert identification of the snake.

A single vial of monovalent brown snake antivenom may be sufficient if there is expert identification of the snake and based on discussion with a clinical toxicologist or a poisons information centre.

A single vial of polyvalent antivenom is recommended if:

  • there is significant doubt about the snake type
  • there is a likelihood of mulga snake, death adder or taipan envenoming, particularly in the following scenarios
    • suspected death adder envenoming with isolated neurotoxicity
    • suspected taipan envenoming in patients in far northern Australia with VICC, with or without neurotoxicity
    • suspected taipan, death adder or mulga snake bites in snake handlers
    • suspected mulga snake bite based on location and nonspecific systemic symptoms (eg nausea, vomiting, headache, abdominal pain, diarrhoea), with or without anticoagulant coagulopathy.
Note: Avoid using polyvalent antivenom in areas where the most likely snake envenomings are covered by monovalent brown snake and monovalent tiger snake antivenoms.
1 Johnston CI, Ryan NM, Page CB, Buckley NA, Brown SG, O'Leary MA, et al. The Australian Snakebite Project, 2005–2015 (ASP-20). Med J Aust 2017;207(3):119–25. [URL]Return