Call 911 if:
- The person displays signs of a severe allergic reaction.
- The sting is from a box jellyfish.
- The sting covers more than half an arm or leg.
1. Get the Person Out of the Water
2. Stop the Stinging
- Wash the area with seawater to deactivate stinging cells. Or you can remove tentacles by scraping with a credit card or other plastic object.
For a sting in tropical waters -- especially from the Hawaiian box jellyfish or a Portuguese man-of-war:
- After removing the tentacles, immerse the affected arm or leg immediately in hot water at 40 to 45°C (104 to 113°F) for at least twenty minutes. A hot shower can be used instead for other parts of the body.
- Anti-venom is available for severe Australian box jellyfish stings. It should be given right away to be most effective.
3. Decontaminate and Remove Tentacles
For jellyfish stings, the American Heart Association recommends the following:
- Rinse the area with vinegar for at least 30 seconds. If vinegar is not available, a solution of baking soda can be used. This will help deactivate the stinging cells.
- Next, soak the area in hot water for at least 20 minutes if possible. Cold packs can be used instead if the area can’t be soaked in hot water.
These treatments are based on research done in the Indo-Pacific areas, however, and may not be effective in the oceans of the North Atlantic. In fact, in this area, vinegar may actually make the symptoms worse, depending on the type of jellyfish. Some experts therefore recommend removing the stinging cells and rinsing in seawater.
4. Treat Discomfort
5. Follow Up
For less severe sting:
- Use ice packs or over-the-counter pain relievers for welts.
- Clean open sores 3 times a day and apply antibiotic ointment. Bandage if needed.
For a severe reaction:
- The person may be hospitalized for several days.
- Anti-venom may be administered for box jellyfish stings.