H.Tanaka/ShutterstockThere are horror stories about box jellyfish, which have tentacles that can reach up to 10 feet in length and carry a half million venomous cells. But they’re a concern in Australia; off North American shores, most people are stung by sea nettle jellyfish, whose tentacles can measure up to six feet in length. Their sting can produce a painful rash that lasts for anywhere from an hour to a day. Although the rash will typically clear up on its own—no medical intervention necessary—it will definitely hurt.
What to do? Before anyone starts unzipping, the first step is to remove any tentacles left behind, advises Cindy Parker, DO, an emergency medicine physician at Kaiser Permanente in Southern California. “Wear gloves and use tweezers,” she says.
Don’t be tempted to rinse the jellyfish sting with fresh water, warns Dr. Parker: This will stimulate stingers, releasing more venom. Here’s where the urine myth dies: Although it contains salts and electrolytes, urine is typically too diluted; like fresh water, it’s more likely to make the pain worse.
“Vinegar, or rubbing alcohol (40-70 percent) can be used to wash off stinging cells,” says Dr. Parker. Again, she warns, don’t use bare hands. Applying a paste of baking soda mixed with water can ease the immediate sting. “You can continue these methods for 30 minutes or until pain eases.”
Next up, go after any remaining stinging cells. Try shaving the area using the baking soda paste, she says, or shaving cream. No razor? You could scrape the area with a credit card. “After that, try controlling the pain with over-the-counter medications (like Tylenol),” says Dr. Parker.