Stung by a Jelly? Get Yourself in Hot Water

Luiz Eduardo via Wikimedia Commons // CC BY 2.0
Luiz Eduardo via Wikimedia Commons // CC BY 2.0 / Luiz Eduardo via Wikimedia Commons // CC BY 2.0

Worried about shark attacks at the beach? Don’t be. Shark encounters are extremely rare, and growing rarer as shark populations decline. But while you likely don’t need to worry about sharks, jellies* might a legitimate cause for concern.

Every year, beachgoers report more than 150 million stings by jellies and other cnidarians, yet there’s still a lot of confusion about the best way to treat them. Two researchers from the University of Hawaiʻi at Mānoa reviewed all of the scientific literature on the subject and came up with one very clear recommendation: use heat. They published their findings in the open-access journal Toxins.

A sting, or envenomation, happens when a person or other animal brushes against a cnidarian’s nematocysts, or stinging cells, which fire tiny harpoons of venom into the hapless swimmer’s skin. Like bee stings, jelly envenomations can result in minor pain or discomfort, but they can also be fatal.

As venom experts and Hawaiians, authors Angel Yanagihara and Christie Wilcox were getting pretty fed up with the amount of bad jelly sting advice on the Internet.

"It’s not too strong to point out that in some cases, ignorance can cost lives," Yanagihara said in a press statement. "We conducted this study to rigorously assemble all the published data in hopes that policy makers will revisit this issue and carefully consider the available evidence. We are also engaged in new experimental work with models looking at vinegar effects, as well as well-designed randomized clinical trials.”

Yanagihara and Wilcox reviewed more than 2000 scientific studies on the use of heat or cold as treatment for jelly envenomation. They found a few studies supporting the use of cold water or ice packs, but most found that cold was ineffective on a sting or even made it worse.

They also found a few reports of people using wine, urine, manure, mustard, ammonia, alcohol, gasoline, or a whole fig. None of these treatments were effective. Only one remedy consistently reduced the pain and other symptoms of envenomation: heat, especially immersing the site of the sting in hot water. And not once did heat treatment make someone’s symptoms worse. Heat treatment is already accepted as the best treatment for stings with other marine venoms, yet somehow it hasn’t caught on for jelly stings.

“I was shocked that the science was so clear, given that there is so much debate over the use of hot water,” Wilcox said. “It’s simple, really: If you’re stung, use hot water or hot packs rather than ice or cold packs.”

And don’t pee on it.

*Scientists prefer the term “jellies” over “jellyfish,” since these invertebrates are not actually fish.