For anyone who has peed on their jellyfish sting (or got a friend to do it for them), I’ve got some bad news. It was completely unnecessary and probably made it worse. A new study has found that simply applying vinegar to the sting, followed by heat, is the best solution regardless of what species has stung you, going against decades of first aid procedures.

The current protocols recommended for stings by the man o’ war jellyfish (Physalia physalis), and its closely related counterpart, the bluebottle (Physalia utriculus), involve washing the affected area with salt water before scraping away the tentacles and applying an ice pack, in order to lessen the impact of the sting. It turns out that this is just about the worst thing you could do.

The process of scraping away tentacles has been found to apply more pressure to the area, which increased the firing of stinging capsules, meaning more venom was injected. Washing in salt water was found to spread the sting over the skin, increasing the area of skin that is actually stung. Adding ice packs to the region just made the pain even worse, reports a new study published in the journal Toxins.

Instead, the researchers found that the general treatment recommended for all other jellyfish stings, namely dowsing the affected area in vinegar, was equally as effective for man o’ wars. Not only that, but the researchers claim that the addition of heat to the stung skin – around 45 minutes of 45°C water or a heat pad – effectively inactivated the venom that had already been injected.

It has long been thought that species of jellyfish belonging to Physalia, which are not technically jellyfish but actually a colony of zooids, require different treatment to the blanket first aid practices recommended for true jellies. Yet after looking at why doctors recommend salt water and ice, and other old wives tale remedies that have risen up, such as lemon juice, shaving foam, and the infamous pee, researchers from Hawaii and Ireland could find no real evidence to back the claims up.

“Without solid science to back up medical practices, we have ended up with conflicting official recommendations around the world, leading to confusion and, in many cases, practices that actually worsen stings or even cost lives,” explained Angel Yanagihara, the senior author of the paper. To test the effectiveness of various treatments, the researchers used sheep and human blood cells in agar.

The research was carried out using the same methods as an earlier study looking into box jellyfish, and will now use it again to test lion’s mane jellies, to see if the same treatment really does hold true over a wide range of species.