Jellyfish stings: first aid that works

Three days of east wind in January, purple floats strung down the Smathers Beach tide line like party trash, and a ten-year-old on my table with a red lash mark wrapped around one calf. Man o' war season, on schedule. Here is the whole first aid kit in one breath. Get out of the water. Rinse the skin with seawater, never fresh water. Lift the tentacles off with a card edge or tweezers, never a bare hand. Then soak the sting in hot water for the pain. And if there is any trouble breathing, any swelling of the face or throat, that is a 911 call before anything else on this list.

Who stings here, and when

Warm months bring moon jellies and sea nettles, the everyday summer stings, more nuisance than emergency for most people. Winter brings the famous one. The Portuguese man o' war rides the winter easterlies onto the Atlantic-side beaches, and despite the reputation it is not a true jellyfish at all but a colonial siphonophore, a floating committee of specialized animals, which matters only in that its tentacles are long, its sting is memorable, and, per Florida FWC seasonality, it arrives most reliably December through March. The critical local fact: a man o' war stranded on the sand, or a tentacle snapped off and lying alone, still fires. Dead is not the same as disarmed. That is why the rule at Smathers is look before you let the dog or the toddler run the tide line.

First aid that works

Out of the water first, before anyone inspects anything, because a second sting while you crouch to look is the classic sequel. Rinse with seawater, not fresh: fresh water changes the salt balance around the stinging cells and makes the unfired ones discharge, turning a rinse into a second dose. Lift visible tentacles away with tweezers or the edge of a credit card, keeping bare fingers clear. Then the best-supported pain treatment: hot water immersion, roughly 104 to 113°F, for 20 to 45 minutes. A 2016 review in the journal Toxins and the 2023 Cochrane review both land on heat over ice, because the venoms are heat-labile and hot water breaks them down. Bath-hot, not scalding, and test it on your own arm first, especially for a child, whose skin scalds faster than yours and who will not thank you for trading a sting for a burn. If a shower is closer than a bucket, run it as hot as tolerable over the sting; the immersion is ideal, but hot running water is a fine field substitute.

The vinegar question, honestly

Vinegar is where confident advice should get nervous. For box jellyfish, the tropical Pacific kind, vinegar is clearly correct and stops undischarged stinging cells from firing. For the Portuguese man o' war, our winter visitor, the evidence is genuinely mixed and has reversed more than once: some studies show vinegar triggering more discharge rather than less. So here is my honest position, current as of this writing. I do not lead with vinegar for a man o' war sting here; I go straight to tentacle removal and hot water, which the evidence supports across species. If all you have is vinegar and a box jelly on the far side of the world, different column. On this island, heat is the reliable answer.

The folk remedies, retired

Urine: no, and I covered this at length in the mailbag because someone always asks. It does nothing helpful and can provoke more firing. Meat tenderizer: no reliable benefit and a nice way to irritate raw skin. Rubbing with sand: actively bad, because it crushes stinging cells against the skin and drives them in. Pressure bandages: for certain snakebites, not for jellyfish stings, where they can worsen things. The shortlist that survives contact with evidence is short on purpose: seawater, tentacle removal, heat, and a clear head about when to call for help.

Recovery, honestly

Most stings settle over hours to a couple of days. The surprise is the itch, which can return in waves for a week or two as the skin works through the reaction, sometimes flaring a faint outline of the original lash. That is normal healing, not reinfection. A mild over-the-counter antihistamine and a plain moisturizer help the itch far more than scratching does, and scratching a healing sting is how people import a second, avoidable infection. What is not normal is a rash that spreads, worsens, or blisters over days rather than fading; that earns a look. The urchins are the other bare-foot lesson at the shoreline, written up in the sea urchin column, and if your sting came with a reef scrape, the coral cuts column takes that half.

Questions from the beach

Sources

• Wilson et al., 2016, Toxins (hot water immersion favored over ice for cnidarian stings; venoms are heat-labile).
• Cochrane systematic review of jellyfish sting interventions, 2023 (heated water immersion, 40 to 45°C, for pain relief).
• Florida Fish and Wildlife Conservation Commission (Portuguese man o' war winter seasonality on Atlantic-side beaches; a siphonophore, not a true jellyfish).
• NOAA Ocean Service (beached animals and detached tentacles still sting).