Irukandji syndrome

Irukandji Syndrome (Carukia barnesi)

Irukandji syndrome is a distressing envenoming secondary to the sting of Carukia barnesi and other, as yet unidentified, jellyfish found in coastal waters of tropical Australia. It has also been reported in Hawaii, the Caribbean, Asia and Papua New Guinea. In a small number of cases, life‑threatening hypertension and pulmonary oedema may develop. Two fatalities have been attributed to this condition in Australia. Management is symptomatic and supportive. Antivenom has not yet been developed.



Venom composition and actions have not been fully characterised. It is thought to induce massive catecholamine release.




Clinical presentation and course
  • The initial sting is usually not felt and there is a short delay to the onset of systemic symptoms. Local signs, such as welts or dermal markings, are minimal or absent
  • Multiple systemic symptoms develop from 30–120 minutes after contact with the jellyfish. These include a sense of impending doom, agitation, dysphoria, vomiting, generalised sweating and severe pain in the back, limbs or abdomen. Hypertension and tachycardia are common.
  • Symptoms usually settle within 12 hours
  • Severe envenoming manifests within 4 hours with on‑going significant opioid requirements. These patients are at risk of toxic cardiomyopathy, cardiogenic shock and pulmonary oedema and may require intubation and mechanical ventilation
  • Intracerebral haemorrhage occurred in two patients within 3–4hours of the sting, presumably due to uncontrolled hypertension.


  • Apply generous volumes of vinegar to all visible sting sites to inactivate all undischarged nematocysts (sting cells)
  • Do not apply a pressure immobilisation bandage (PIB)
  • Transport all patients with pain refractory to first‑aid, or systemic symptoms to a medical facility – this is a potentially life‑threatening emergency
  • Potential early life‑threats that require immediate interventioninclude:
  • — Severe hypertension
  • — Pulmonary oedema
  • Administer IV fentanyl (0.5–1.0 microgram/kg/dose) repeated every 10 minutes until appropriate analgesia is achieved. Large doses may be required (e.g. 200–300 microgram). Note: If fentanyl is not available, give morphine 0.1 mg/kg IV in titrated doses
  • Treat nausea with IV promethazine (25 mg; 0.5 mg/kg in children)
  • Control hypertension refractory to opioid analgesia with an intravenous infusion of glyceryl trinitrate (50 mg in 100 mL starting at 6 mL/minute; 1–4 microgram/kg/minute in children) titrated to achieve a systolic blood pressure <160 mmHg
  • Manage pain refractory to opioids with IV magnesium (0.2 mmol/kg up to 10 mmol in adults) administered over 5–15 minutes. Seek expert advice


  • None available.



Differential diagnosis
  • Envenoming by the box jellyfish (Chironex fleckeri) is associated with immediate pain and obvious dermal markings (large welts). Tentacles may be seen adherent to the skin
  • Bluebottle stings (Physalia species) are associated with immediate pain and dermal markings. The pain usually resolves within 1 hour and systemic symptoms are extremely rare
  • Decompression illness may lead to generalised pain or collapse shortly after a diver has surfaced. Welts are not seen
  • Redback spider envenoming (Latrodectus hasseltii) causes bite site pain and sweating, followed by more generalised pain, sweating and dysphoria. It is associated with contact with a spider on land.



Handy tips
  • Clinical features of envenoming occur after the patient has left the water, so they may be unaware they have been stung
  • Irukandji syndrome should be considered in any patient presenting with clinical features during or shortly after swimming in tropical coastal Australian waters
  • Clinical features of dysphoria, severe generalised pain, sweating, hypertension and pulmonary oedema, in the absence of major dermal findings, is pathognomic of irukandji syndrome
  • Patient controlled analgesia may be useful where there is an on‑going opioid requirement.



  • The role of magnesium. Anecdotal evidence suggests that IV magnesium (in the same infusion doses as used in preeclampsia) may have a role in treatment of severe irukandji syndrome.
  • The role of benzodiazepines in the management of symptoms presumed due to catecholamine release
  • The agent of choice to manage hypertension and tachycardia.



Related Links and References:

Clinical cases of Irukandji Syndrome

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    • says

      Fentanyl has these favourable characteristics:
      rapid onset
      can be rapidly titrated
      preserves cardiac stability and blunts stress-related hormonal changes at higher doses
      rarely elicits histamine release
      no toxic metabolites

      Blood pressure is often sufficiently well controlled with fentanyl alone (through analgesic and possibly sympatholytic effects), but the alpha-blockade effect of promethazine (or chlorpromazine which has been as an alternative) or the antihypertensive effects of GTN (rapidly titratable) and magnesium combine tend to do the job.



  1. [...] “Irukandji syndrome” can be caused by the sting of a number of jellyfish, predominantly Carukia barnesi.  This tiny (20 mm) cnidarian is found in the waters off northern Australia. Its sting initially seems minor, but is followed within 30 minutes to an hour with severe manifestations of catecholamine storm: hypertension, tachycardia,  EKG changes, and occasionally cardiomyopathy (Takutsubo). [...]