Folklore and fable hold that the fastest and most convenient way to quell the pain of a jellyfish sting is to urinate on it. They did it on Friends and it seemed to work like magic for Monica. But as warm weather and warm waters bring on the jellyfish season, and we face the possibility of a painful sting while on vacation, should urination be the first thing we try or the absolute last resort?
The Straight Talk
The jellyfish sting hurts because small nematocysts, located on a jellyfish’s tentacles, release venom into the skin upon contact. Any successful remedy must be able to deactivate these nematocysts, and unfortunately, urine doesn’t.
Peeing onto a sting not only does nothing to deactivate these nematocysts, it may actually cause more of them to release their toxin. Urine can therefore make the pain worse, meaning peeing on the wound is a bit like pouring the idiomatic salt on it.
One simple remedy that has worked is acetic acid, or household white vinegar. Researchers in Australia, who are very familiar with the box jellyfish, a species that can potentially cause serious illness and that is prevalent on the north coast, have found that pouring vinegar on the wound deactivates the venom release. In a Medical Journal of Australia article the author writes, “Vinegar dousing may irritate freshly stung skin, but as a nematocyst inhibitor, vinegar remains an essential part of the first aid treatment for cubozoan [box] jellyfish stings.”
Urine, which is only weakly if at all acidic, doesn’t have the strength to stop the sting. Neither does fresh water, which can change the pH and salt content and cause more nematocysts to fire.
If a jellyfish stings you, pour vinegar on the wound, but don’t rub. Although beaches in Australia usually have vinegar stands lining the beach in case someone is stung, that’s not usually the case in the US; if you’re stung here wash with sea water. Remove the tentacles with a cloth or stick (not your hands; it can still sting). If more nematocysts are still visible, wash with sea water, not fresh water.
It’s not clear whether the Portuguese Man-o-War, which isn’t a true jellyfish but is very dangerous, responds in the same way to the vinegar method. Regardless of the source of the sting, if a victim shows signs of shock—shortness of breath, vomiting, hypertension—they should see a doctor immediately.
Keep the bathing suit bottoms on and turn the pain off with vinegar.
Say What? is a series created to support or debunk common health myths. If you have a question for Brie, please send it to her at firstname.lastname@example.org.
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Updated June 9, 2010