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.