Yeah but thats how the box jelly kills people.

it doesnt kill them through skin scaring or pain.

it doesnt kill all of them.. just like heart attacks. in fact a super majority of people only have pain.. i suspect the antidote would be used for those at most risk.. the elderly and kids.

but when it does kill them, its from the heart attack.

So its kinda a crucial part of the antidote, that it actually stops the only avenue of death from these things.