Jellyfish sting: 6 steps that relieve the pain and the false remedies to forget

By the Spotmydive editorial team · 2 February 2024

This article is for information only and does not replace advice from a doctor trained in diving medicine.

Between 2015 and 2024, French poison control centers recorded 1,311 cases of stings from marine animals, according to a review published by Anses, the French food and health safety agency, in July 2026. Jellyfish account for 19% of those cases. The Portuguese man o’ war, 13%.

That figure only counts the calls. Most stings get handled at the lifeguard station or with the habits people pass down in their families, and some of those habits make the pain worse instead of calming it.

The old version of this article promised “8 remedies.” After cross-checking official guidance and the scientific literature, we kept six steps that hold up, and set aside a few false remedies (including vinegar, which our own FAQ used to recommend without any nuance).

Contents

What should you do right after a jellyfish sting?

Get out of the water, then rinse the area for a long time with seawater, never with fresh water. Next, remove the bits of tentacle without crushing them, using shaving foam or dry sand, then something rigid. Rinse again and disinfect. That is the sequence Anses published in July 2026.

Get out of the water and alert the lifeguard station if there is one.
Rinse generously with seawater.
Lift off the tentacles without rubbing: shaving foam or dry sand, then a rigid card.
Rinse again with seawater, then disinfect with an antiseptic or an anti-inflammatory cream.
Ease the pain with heat or with wrapped cold (details below).
For a Portuguese man o’ war only: rinse with seawater mixed with vinegar.

The sand has to be dry. Wet sand sticks to the skin and tempts you to rub, which the fact sheets of the regional health agencies (ARS) of Brittany and Normandy in France clearly advise against (undated documents, consulted on October 3, 2026).

Rinsing with seawater is no second-best option. The 2016 review published in Marine Drugs by Montgomery and colleagues, which focuses on European jellyfish, lists it among the treatments with documented positive effects, both for detaching tentacles and for easing pain. On a boat, it is also the only water you have in quantity. Slip a rigid card into your kit. It costs nothing.

So the step people skip most often is still the first one: get out of the water before anything else.

Urine, fresh water, rubbing: why do these habits make a sting worse?

Fresh water and rubbing make the stinging cells still stuck to your skin fire. These nematocysts are tiny venom harpoons, and a mechanical shock or a change in salinity is enough to trigger them. As for urine, no study supports it. Health authorities advise against it.

Montgomery et al. (2016) describe the fresh water mechanism without ambiguity. A change in osmotic concentration can make intact nematocysts discharge, which intensifies the initial sting, hence the rule never to rinse with tap or bottled water. The beach shower can wait. Put ice in a bag, then in a cloth, never directly on the skin. In short, as long as filaments remain on your skin, fresh water stays off the table, bare ice cubes included.

The urine myth refuses to die. Yet the French regional health agencies list it among the things not to do, and the authors of the 2016 review dispute that urine could be presented as a suitable treatment, since there is no evidence at all that it works.

Add ammonia to the list, which the same agencies also rule out.

Habit	Verdict	What the sources say
Rinsing with fresh water	Avoid	Can make nematocysts discharge (Montgomery et al., 2016). Ruled out by Anses (2026).
Urinating on the sting	Avoid	No proven benefit. Advised against by the French regional health agencies.
Rubbing, scratching	Avoid	Triggers more nematocyst discharge (Montgomery et al., 2016).
Vinegar on any jellyfish	Depends on the species	Recommended by Anses for the Portuguese man o’ war only. Conflicting results on other species.
Ammonia	Avoid	Advised against by the French regional health agencies.

Should you put vinegar on a jellyfish sting?

It depends on the species, and on French coasts the answer is usually no. Anses recommends vinegar only for the Portuguese man o’ war, diluted in seawater. For jellyfish, its 2026 fact sheet sticks to seawater, and the French regional health agencies advise against vinegar.

The confusion goes back a long way. Vinegar works on some species, and some English-language pages apply it to all of them, like the one DAN Southern Africa published in 2016, which advises flooding the wound with 5% vinegar without distinguishing between jellyfish. Yet the Montgomery et al. review counts almost as many unfavorable studies as favorable ones. It only keeps vinegar for two European species, Carybdea marsupialis and Chrysaora hysoscella. For Pelagia noctiluca, very common in the Mediterranean according to the same work, published results contradict each other from one study to the next.

For the Portuguese man o’ war, Anses gives the dose: one part food-grade white vinegar (5 to 8%) to three parts seawater.

You won’t always know what stung you. When in doubt, seawater alone is the advice shared by every source we checked. But if a bluish or purple float is drifting on a beach in the Landes or the Basque Country, where Anses reports regular Portuguese man o’ war sightings, diluted vinegar becomes a reasonable option while you wait for the lifeguards’ advice.

Hot or cold: what eases the pain best?

Heat has the best data. The 2016 review settles on immersion in water at 42 to 45 °C (108 to 113 °F) for 30 minutes, or until the pain subsides. Cold, wrapped in a cloth, remains a fair option for a mild sting, with no side effects reported according to the same authors.

Handle that 45 °C figure with care. Anses, which recommends heat for weever fish stings, caps it at 42 °C (108 °F), and that is the cap we would keep for a child’s skin or skin that is already raw (our editorial view, not medical guidance). Test the water on your own healthy skin. No need to add a burn. On a boat, a wrapped cold pack is often the simplest solution.

However, the itching that follows can last several days, Anses warns.

Baking soda, mentioned in our old FAQ, appears in the sequence proposed by Montgomery et al., but Anses does not mention it. A pharmacist can suggest a suitable cream. The “30 minutes to 2 hours” of pain that the old version gave had no source. The French regional health agencies set a more useful marker: if the pain lasts beyond 30 minutes, see a doctor.

Which warning signs mean you should call emergency services?

Call the local emergency number (112 in the EU) in case of fainting or feeling unwell, breathing difficulty, chest or abdominal pain, vomiting or involuntary muscle contractions. Anses describes these general symptoms for the Portuguese man o’ war, where they appear in about 15% of observed cases.

Breathing difficulty, swelling of the face or throat, fainting: call 112 or your local emergency number right away.
Dizziness, headache, drowsiness, fever, nausea: general symptoms listed by the French regional health agencies, to be checked quickly.
Extensive sting (a whole arm or leg), on the face or genitals, in a very young child or an elderly person: get medical advice, according to DAN Southern Africa (2016).
Pain beyond 30 minutes or a wound that is healing badly: see a doctor.

When life is not at risk, poison control centers can also help. In France, Anses points to centres-antipoison.net to find your regional center’s contact details. Save that link on your phone.

For a diver, the question changes. Picture a sting to the face halfway through a dive: the pain pushes you to ascend fast, and the ascent becomes the real danger. Signal it to your guide, then ascend with your group at the speed and with the safety stop planned in the briefing. Our article on managing stress to respond better in difficult situations underwater covers that reflex in more depth. Once back on the boat, the sequence stays the same. And if general symptoms appear, getting back in the water is a decision to make with a doctor trained in diving medicine.

The club does not have to decide alone.

How can you lower the risk when snorkeling or diving?

Choose a supervised area and follow local signs, as Anses advises. A wetsuit or a rash guard covers your arms and legs, which reduces the skin exposed to filaments drifting near the surface. But none of these steps removes the risk. They lower it, and they keep you within reach of a lifeguard station if things go wrong.

Jellyfish blooms vary from one year to the next, and their likely causes (warming, overfishing, pollution) are covered in our feature on jellyfish invasions and their consequences for biodiversity. Stinging cells are one of the tools described in our piece on extraordinary defense mechanisms in marine animals.

Before a snorkeling trip, always check the day’s notice at the lifeguard station. Look at a stranded Portuguese man o’ war from a distance, because its venom stays active out of the water according to Anses, and the rule applies to all marine life: don’t touch it. A rash guard pulls double duty. It protects your skin and cuts down the amount of sunscreen that ends up in the water.

The cost of this caution is counted in minutes, the ones it takes to stop by the lifeguard station before you get in.

FAQ

What should you do immediately after a jellyfish sting?

Get out of the water and rinse the area with seawater, never fresh water. Remove the tentacles with shaving foam or dry sand, then a rigid card, without rubbing. Rinse again and disinfect, as Anses recommends (2026).

Should you pee on a jellyfish sting?

No. No study shows any benefit, and French regional health agencies advise against it. Seawater is the only liquid to use for rinsing.

Does vinegar relieve a jellyfish sting?

It depends on the species. Anses recommends it only for the Portuguese man o’ war, diluted at one part vinegar to three parts seawater. For other jellyfish, studies contradict each other, and seawater alone remains the standard advice.

When should you see a doctor after a jellyfish sting?

See a doctor if the pain lasts more than 30 minutes, if the wound heals badly, if the sting is on the face or covers a large area, or if the person stung is a very young child. Call 112 or your local emergency number in case of fainting, breathing difficulty, vomiting or chest pain.