The short version
- The 2025 ILCOR systematic review found very low-quality evidence for every jellyfish first aid method and recommends seawater as the default rinse, because it is free and always at hand[1].
- For Portuguese man-of-war (bluebottle) stings, hot water at 45 °C beat ice packs in a 96-patient trial, with a 42% matched difference in pain reduction[1].
- Rinse with salt water, not fresh water, which can fire the stinging cells left on the skin[4].
- Most deaths occur in the Indo-Pacific from box jellyfish, and only one antivenom exists, for Chironex fleckeri[2].
What the evidence says about each treatment
| Treatment | Finding in the ILCOR review[1] |
|---|---|
| Seawater rinse | Recommended first step, given its availability at no cost |
| Hot water, 45 °C | Better than ice in one trial (bluebottle), no different from ice in another (box jellyfish) |
| Lidocaine, sea salt solution | Better than no treatment in small studies |
| Vinegar | Most studied (7 studies); in two studies it gave worse pain than no treatment |
| Ethanol, ammonia | Worse pain than no treatment |
The review covered 7 randomized or quasi-randomized trials and 3 non-randomized studies, and every result carried very low confidence[1]. That is why the advice changes with species: no single treatment is best for all jellyfish[3].
The two hot water trials
| Trial[1] | Jellyfish | Result |
|---|---|---|
| Loten et al., 2006, 96 patients | Physalia (bluebottle, man-of-war) | Hot water 45 °C for 20 minutes beat ice; matched difference 42%; less radiating pain; no burns |
| Isbister et al., 2017, 46 patients | Chironex fleckeri (box jellyfish) | After vinegar, hot water and ice gave similar relief at 30 minutes (11 of 17 vs 14 of 25) |
Jellyfish sting treatment, step by step
- Get out of the water before treating anything.
- Rinse with seawater, not fresh water[1][4].
- Remove visible tentacles with tweezers or a gloved hand; removing tentacles is one aim of first aid[4][1].
- Soak in hot water around 45 °C (113 °F) for about 20 minutes if available, or use a cold pack if not[1].
- Treat the itch and rash with an antihistamine and hydrocortisone cream; check tetanus status[4].
When a jellyfish sting is an emergency
Allergic reactions are possible[4], and stings can cause systemic symptoms and, rarely, death[2]. Breathing trouble, collapse, chest pain or a sting over a large area at sea means radio medical advice at once and a medevac decision. Pain that flares again days later also needs review[4].
Why crews see more stings in summer
US Google searches for “jellyfish sting treatment” ran at 18,100 in August 2026 against 1,300 in February (DataForSEO). Contacts between people and jellyfish are high and increasing, and the 2022 review authors link rising case numbers partly to climate change[2].
| Who is exposed | Practical step |
|---|---|
| Deckhands hauling nets and lines | Wear gloves when clearing tentacles from nets and lines |
| Divers and swimmers from vessels | Cover exposed skin in known jellyfish areas; see commercial diving medical rules |
| Everyone | Do not handle jellyfish or jellyfish parts on deck or beach (Poison Control)[4] |
Related marine injuries: fish handler’s disease and cold water immersion.
Discovery Health MD turns this evidence into a vessel protocol: maritime medical consulting for species-aware sting first aid, and ship medical chest management for lidocaine, antihistamines, steroid creams and a thermometer in the chest. Ask a physician to set up your sting protocol.
Common questions
What is the best treatment for a jellyfish sting?
Rinse with seawater, remove tentacles and use hot water around 45 °C or a cold pack for pain; the evidence for every method is very low quality[1].
Does vinegar help jellyfish stings?
It is the most studied treatment, but results are mixed and two studies found worse pain than no treatment[1].
Should you pee on a jellyfish sting?
None of the studies in the 2025 ILCOR review tested urine; seawater is the recommended rinse[1].
Hot or cold for a jellyfish sting?
Hot water beat ice for bluebottle stings in one trial; for box jellyfish they were similar[1].
Should you rinse a jellyfish sting with fresh water?
No. Use salt water; fresh water may discharge stinging cells[4].
How long does a jellyfish sting last?
Time to pain relief in the studies ranged up to 24 hours, and symptoms can flare again days later[1][4].
Can a jellyfish sting kill you?
Rarely; most deaths happen in the Indo-Pacific from box jellyfish[2].
