Irukandji Jellyfish

Inadvertent contact with this aquatic species causes excruciating pain and an overwhelming sense of impending doom.  What is this?

  1. Box Jellyfish (Chironex fleckeri)
  2. Irukandji Jellyfish (Carukia barnesi)
  3. Lion’s Mane Jellyfish (Cyanea capillata)
  4. Portuguese Man o’ War (Physalia physalis)

Answer: 2 – Irukandji Jellyfish (Carukia barnesi)

What is Irukandji Syndrome [1-4]?

  • Irukandji Syndrome is a sensation of extreme pain and agitation and a feeling of impending doom following envenomation by the Irukandji jellyfish and associated species.
  • This jellyfish is most commonly found in Northern Australia but the syndrome has been described throughout the tropics, including Hawaii and northern Florida.
  • The jellyfish is small (5 mm body with up to 100 cm long tentacles) and may not be noticed by the swimmer.
  • Its venom is delivered via nematocysts and is thought to cause toxic modulation of neuronal sodium channels leading to excessive catecholamine release.

What is the clinical presentation of Irukandji Syndrome [2-8]?

  • A mild sting (which can easily go unnoticed), a latent period of 10-45 minutes, then a rush of systemic symptoms
  • Local erythema and piloerection may be seen in the shape of the bell or tentacles.
  • Excruciating chest, back, and abdominal pain with significant muscle spasms
  • Nausea, vomiting, and anxiety
  • A sense of impending doom
  • Severe hypertension is almost universally present initially
  • Cardiogenic shock may follow initial hypertension and require pressor support
  • Life-threatening sequelae include pulmonary edema, toxic cardiomyopathy, and intracranial hemorrhage, with fatalities reported

What is the treatment of Irukandji syndrome [2,6,9-11]?

  • Vinegar (acetic acid) can be applied to envenomation site to inactivate nematocysts that have not yet fired. This is followed by careful removal of any retained tentacles.
  • Pain management often requires large doses of opioids.
  • Supportive care for nausea, vomiting, anxiety.
  • Antihypertensives may be required; titratable agents such as esmolol are preferred as shock may develop later.
  • About half of patients may require admission, with some requiring ICU level care.
  • Intravenous magnesium salts have been proposed as an adjunct treatment for severe Irukandji syndrome but research to date is equivocal.

Clinical Pearls

  • Initially thought to be confined to the Northern Australian coast, Irukandji syndrome has been reported throughout the tropics.
  • The syndrome begins with mild sting and a latent period followed by severe systemic symptoms of excruciating pain and sequelae of a catecholamine surge.
  • First aid includes dousing in the site with vinegar (acetic acid) for 30 seconds and removing any tentacles.
  • Treatment is ABCs, then pain control with IV opioids along with antiemetics, anxiolytics, and antihypertensives.
  • May require admission and possible ICU level care for life-threatening complications.

This item was peer-reviewed on behalf of ACMT by Dr Eike Blohm, Dr Bryan Judge, and Dr Louise Kao.

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    1. Tibballs J, Li R, Tibballs HA, Gershwin L-A, Winkel KD. Australian carybdeid jellyfish causing “Irukandji syndrome.” >Toxicon. 2012;59(6):617–25. PMID: 22361384
    2. Blohm E & Brush E.  Marine Envenomations.  In: Goldfranks Toxicologic Emergencies 11th Edition; Eds Nelson L howland MA Lewin NA et al. McGraw Hill, New York, NY, 2019.
    3. Grady JD, Burnett JW. Irukandji-like syndrome in South Florida divers.Ann Emerg Med. 2003 Dec;42(6):763-6. PMID: 14634600.
    4. Dawson AH. Fatal envenomation by jellyfish causing Irukandji syndrome. Med J Aust. 2003 Feb 3;178(3):139; author reply 139-40. PubMed PMID: 12776732
    5. Carrette TJ, Underwood AH, Seymour JE. Irukandji syndrome: a widely misunderstood and poorly researched tropical marine envenoming. Diving Hyperb Med. 2012 Dec;42(4):214-23. Review. PMID: 23258458
    6. Nickson CP, Waugh EB, Jacups SP, Currie BJ. Irukandji syndrome case series from Australia’s Tropical Northern Territory. Ann Emerg Med. 2009 Sep;54(3):395-403. PMID: 19409658
    7. Fenner PJ, Hadok JC. Fatal envenomation by jellyfish causing Irukandji syndrome. Med J Aust. 2002 Oct 7;177(7):362-3. PMID: 12358578
    8. Australian Resuscitation Council. Envenomation: Jellyfish Stings (guideline 9.4.5) July 2010. Accessed April 2020
    9. Fenner P, Carney I. The Irukandji syndrome. A devastating syndrome caused by a north Australian jellyfish. Aust Fam Physician. 1999 Nov;28(11):1131-7. PMID: 10615756.
    10. Rathbone J, Franklin R, Gibbs C, Williams D. Review article: Role of magnesium sulphate in the management of Irukandji syndrome: A systematic review. Emerg Med Australas. 2017 Feb;29(1):9-17. PMID: 27748058
Christopher Gardner, MD

Christopher Gardner, MD

Emergency Medicine Resident
Carolinas Medical Center, Charlotte, NC
Christopher Gardner, MD

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Kathryn T. Kopec, DO

Kathryn T. Kopec, DO

Emergency Medicine and Medical Toxicology Faculty
Carolinas Medical Center, Charlotte, NC