How To Fix a Jellyfish Sting

Pack tweezers and vinegar in your beach bag—and forget what you’ve heard about the pee cure.

Published May 10, 2017

Nothing ruins a day at the beach faster than a jellyfish sting. The animal’s venomous tentacles can stick to arms and legs, delivering burning pain to a large swath of skin. In severe cases, the stings can be life-threatening. And yet, the most common first-aid guidelines not only fail to ease the pain, they can even make the sting worse.

In a new research paper, scientists tested different ways of treating jellyfish stings and revealed some surprising finds. Rinsing with seawater, for example, only spreads the sting to a larger area. Scraping off the tentacles with a credit card—a method recommended even by well-respected healthcare organizations—is an equally bad strategy. Scraping the wound applies pressure that causes stingers to release more venom.

“When I first started doing this research I was surprised that a lot of this advice doesn’t really come from science,” says Christie Wilcox, a venom scientist at the University of Hawai‘i, and coauthor of two recent studies on jellyfish sting treatment. And before you ask: no, you shouldn’t pee on the wound.

In a best-case scenario, pee will act as a neutral solution that just moves the tentacles around, says Wilcox. But urine doesn’t have a consistent chemical makeup, she says. Depending on various factors, such as whether a person is dehydrated and what they’ve eaten that day, urine might actually contain chemical compounds that trigger stinging cells to fire. “It can cause massive stinging,” she says. 

To stop the sting and bring relief, Wilcox recommends a three-step treatment:

  1. Douse the area with vinegar, to rinse away the tentacles and deactivate the stinging cells. If you do this first, you won’t spread the sting to other areas when you attempt to remove the tentacles.
  2. Pluck off the tentacles with tweezers. Scraping them off or rubbing with sand (another recommended approach) triggers any active stingers to release more venom, so you want to delicately lift the tentacles off the skin.
  3. Apply heat.

While many medical professionals advise ice, and an ice pack may indeed temporarily numb the area, cold preserves the venom that’s already been injected, and in some cases may even enhance the action of the toxin, Wilcox says. Instead, heat permanently inactivates the venom, she says.

In two separate studies published in the journal Toxins, researchers looked at treatments for both the box jellyfish (some species of which can be fatal in severe cases) and the Portuguese man-of-war. They found that the same advice applies, regardless of which type of animal caused the sting. “You don’t have to be a jelly expert to know what to do,” Wilcox says.