...quoting head of British Red Cross first aid Joe Mulligan.
“If people have been stung, they need to get out of the water to avoid getting stung again. Once out, slowly pouring seawater over the sting will help ease the pain.
“Doing the same thing with vinegar can be even more effective as the acid helps neutralise the jellyfish sting. But, unless you’re near a chip shop, seawater will probably be easier to find.”
Emergency physician Dr. Ryan Stanton, who's spent some time in Australia and is familiar with the country's venomous box jellyfish, agrees. The efficacy hierarchy here is this: vinegar, isopropyl alcohol, ocean water --
then urine, explains Stanton, now the medical director at UK HealthCare Good Samaritan Hospital in Lexington, Ky.