Box jellyfish envenomation

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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
  • 83% occur in < 1m of water.
  • Most stings are benign (requiring local treatment only), recent data suggests fatality rate is much lower than the 20% previously reported.
    • Morbidity and Mortality are dose- and time-dependent, which explains why majority of deaths have been children.


  • Has about 15 tentacles (measure up to 3m in length) that contain millions of "stinging cells" called nematocysts.
  • Contact with the tentacles cause rapid onset of pruritic/burning
  • Thought to affect sodium/potassium/calcium channels
  • Rhabodmyolysis can occur from sustained muscle contractions caused by myotoxins in venom.
  • Cardiovascular collapse can occur d/t dysrhythmia (from hyperkalemia) and osmotic dysregulation of endothelial and cardiac tissues from pore-forming toxins within the venom.
  • Chironex fleckeri venom causes cell membranes to become porous allowing K+ influx/hyperkalemia

Clinical Features

Patient stung by multiple box jellyfish tentacles.
Patient stung by multiple box jellyfish tentacles.
Box jellyfish sting.
Pediatric box jellyfish sting.
  • Stings associated with immediate pain, lasting up to 8 hours, and linear welts in a cross-hatched "ladder-rung" pattern
    • Erythematous maculopapular rash
    • 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


  • First remove any tentacles
    • tentacles separated from medusae can still emit venom
  • 4-5% acetic acid/vinegar solution should be applied to the injured area for at least 30 seconds.[2]
  • 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
  • Avoid treating with fresh water, alcohol, methylated spirits, or urine as these have shown to increase nematocyst firing. [3]

Antivenom Indications^

  • Cardiac arrest
    • undiluted antivenom administered as an IV Push: up to 6 vials
    • if no response then give magnesium IV (0.2mmol/kg, max 10mmol in adults)
  • 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. Hauglid, Christopher, DO, et al. “EMERGEN-SEA MEDICINE: An Overview of Sea Urchins, Coral, Starfish, and More.” ACEP Now, vol. 40, no. 7, 2021, pp. 8–9.
  2. Hauglid, C., Kiel, J., & Schmidt, A. (2021, April 23). Emergen-Sea Medicine: Overview of Marine Envenomations - Page 4 of 5. ACEP Now.
  3. Hauglid, Christopher, DO, et al. “EMERGEN-SEA MEDICINE: An Overview of Sea Urchins, Coral, Starfish, and More.” ACEP Now, vol. 40, no. 7, 2021, pp. 8–9.