There has been an anti venom available for many years. This has had to be given intravenously. [Box jellyfish antivenom](https://www.healthdirect.gov.au/medicines/brand/amt,73737011000036105/box-jellyfish-antivenom-csl) .

I guess this is a new topical method of application. Given that a severe sting can cause cardiac arrest within seconds, the intravenous Antivenom will still be the main life saver.