Box jellyfish


Box jellyfish
Nematocyst stages of discharge
  • Cnidarian invertebrates distinguished by their cube-shaped medusae
  • Chironex fleckeri or sea wasp is cause of most deaths
  • Largely restricted to the Indo-Pacific Ocean/Australian waters but various species can be found widely
  • Most stings are benign (requiring local treatment only), only a few species have been implicated in human deaths


  • Specific venom components unclear
  • Thought to affect sodium/potassium/calcium channels
  • Chironex fleckeri venom causes cell membranes to become porous allowing K+ influx/hyperkalemia

Clinical Features

  • Stings associated with immediate pain, lasting up to 8 hours, and linear welts in a cross-hatched pattern
    • May progress to blisters/necrosis
  • 25-30% may still have tentacles attached
  • Systemic envenomation (usually >10% BSA) can manifest as cardiac arrhythmias, respiratory dysfunction, death
    • usually manifests within 5 minutes of sting
  • delayed hypersensitivity reactions occur in >50%
    • Itching, redness at sting sites 7-14d after initial incidence

Differential Diagnosis

Marine toxins, envenomations, and bites


  • Generally a clinical diagnosis


  • Pour liberal amounts of vinegar to inhibit nematocyst discharge[1]
  • Remove any tentacles
    • tentacles separated from medusae can still emit venom
  • Pain control
  • Supportive measures for minor envenomations
    • Ice recommended but heat may actually work better
  • Antihistamines and steroids for hypersensitivity reaction
  • Do NOT pressure bandage
  • Antivenom for life-threatening envenomations
    • Bovine IgG Fab with 20,000 units/ampule

Antivenom Indications^

  • Cardiac arrest
    • undiluted antivenom administered as an IV Push: up to 6 vials
    • if no response then give magnesium IV
  • Hypotension, tachycardia, shock, arrhythmia
    • dilute 3 amps antivenom in 100mL NS and run over 20 minutes
    • can repeat for a total of 6 vials
  • Intractable pain
    • give 1 amp diluted in 100mL NS run over 20 minutes

Anti-venom can cause serum sickness 4-14 days after administration


See Also


  1. Bastian Bentlage, Paulyn Cartwright, Angel A. Yanagihara, Cheryl Lewis, Gemma S. Richards and Allen G. Collins.Evolution of box jellyfishes (Cnidaria: Cubozoa), a group of highly toxic invertebrates. Proceedings of the Royal Society, November 18, 2009 DOI:10.1098/rspb.2009.1707
  2. Currie BJ, Jacups SP. Prospective study of Chironex fleckeri and other box jellyfish stings in the “Top End” of Australia’s Northern Territory. Med J Aust 2005; 183: 631-636
  3. Hughes RJ, Angus JA, Winkel KD, Wright CE. A pharmacological investigation of the venom extract of the Australian box jellyfish, Chironex fleckeri, in cardiac and vascular tissues. Toxicol Lett. 2012 Feb 25;209(1):11-20. Epub 2011 Dec 2.
    1. Yanagihara AA, Wilcox CL. Cubozoan Sting-Site Seawater Rinse, Scraping, and Ice Can Increase Venom Load: Upending Current First Aid Recommendations. Toxins (Basel). 2017;9(3):105. Published 2017 Mar 15. doi:10.3390/toxins9030105