What should you do if a jellyfish stings you? Scientists have found that applying vinegar is the best solution, and that popular remedies including urine, lemon juice, and shaving foam could make the situation worse.
A recent study in Toxins, which investigated the efficacy of various remedies for stings from the Portuguese man o’ war (Physalia physalis) concludes that rinsing with vinegar before applying heat is the most effective treatment. The commonly recommended treatment of seawater and ice was found to cause more harm than good.
Dr Tom Doyle, a biologist at NUI Galway and co-author of the paper, conducted research on both the Atlantic and Pacific man o’ war. He said the findings represented a complete U-turn.
“For me it was certainly surprising as we have been recommending seawater and ice for the last 10 years,” he said. “But that’s the nature of science; we have to hold up our hands and say we were wrong. We went back to basics and tested different methods. There’s no doubt about our findings. We are absolutely 100% certain that vinegar does the trick.”
The scientists tested various solutions on sheep and human blood cells suspended in agar. The method of scraping away tentacles was found to increase pressure on the affected area, causing the stinging capsules to fire more venom into the victim. However, applying vinegar was shown to prevent further venom release, allowing the tentacles to be safely removed. Immersing the area in 45C water or applying a heatpack resulted in fewer red blood cells being killed.
In contrast, rinsing with seawater was found to worsen stings by spreading venom capsules further, while cold packs caused them to fire more venom. The infamous urine theory – popularised by an episode of Friends – was also found to aggravate stings. Baking soda, shaving cream, soap, lemon juice, alcohol and cola yielded similar results.
Although vinegar is used for many other jellyfish stings, the man o’ war has long been considered an exception, with many guidelines warning against its use. While it’s true that the man o’ war is different – they are technically a siphonophore and not a jellyfish – the scientists behind this research are now arguing that all stings be treated equally.
Biologist and jellyfish expert Dr Lisa Gershwin agrees that treatment with vinegar works, but expressed concern about the hot water recommendation.
“Hot water does take away the pain but this is a neurological process; it has nothing to do with denaturing the venom,” she said. “Fresh water activates discharge and by applying heat, you are dilating the capillaries and allowing venom to go further into the body.”
The study was prompted by an influx of man o’ war on European coasts last summer and built upon the findings of a study on box jellyfish conducted by the University of Hawaii at Mānoa. The researchers will now turn their attention to the lion’s mane jellyfish to determine if the same conclusions apply.
(First published in The Guardian UK. Available online at: https://www.theguardian.com/environment/2017/may/09/vinegar-best-antidote-jellyfish-stings-urine-lemon-juice-make-worse-study)