A jellyfish sting can cause anything from a limited burning sensation to severe pain, linear skin marks and, more rarely, a serious systemic reaction. Jellyfish tentacles contain microscopic stinging cells called nematocysts, which release venom when activated. Some may remain on the skin after a person leaves the water and continue to discharge if the area is rubbed or treated incorrectly.

First aid is not identical for every jellyfish species. This is why advice such as “apply vinegar” may be appropriate for one species and harmful for another. In the Mediterranean, where Pelagia noctiluca is common, vinegar is not a universal treatment and may trigger further nematocyst discharge.


Leave the water safely


The first step is to get out of the water, particularly if pain is severe or the person feels dizzy. Do not rub the area with hands, a towel or sand. Rubbing can trigger stinging cells that have not yet released their venom.

The area can initially be rinsed gently with seawater. Fresh water is avoided during the first stage because the change in osmotic pressure may activate additional nematocysts, depending on the species.


How to remove tentacles


Visible tentacle fragments should be removed carefully with tweezers or protected hands. Do not touch them with bare fingers. A plastic card may be used gently to lift residual material without forceful pressure or repeated scraping.

Lifeguards or local authorities may know which species is present and which protocol is recommended. This information matters before using vinegar, a baking-soda mixture, heat or cold.


Why vinegar is not suitable for every species


Vinegar can limit nematocyst discharge in some box jellyfish. Research involving Mediterranean species shows that it can have the opposite effect on Pelagia noctiluca, one of the most frequent causes of stings in the region.

Vinegar should therefore not be applied automatically to every sting. When the species is unknown, follow local lifeguard or public-health guidance and begin with the safest general steps.


Hot or cold treatment?


Immersion in tolerably hot water can reduce pain after many types of jellyfish sting, while protocols for some common Mediterranean species use a cold pack wrapped in cloth. Neither direct ice nor dangerously hot water should be placed on the skin.

Because recommendations vary by species, local official guidance takes priority. Persistent severe pain requires assessment by a healthcare professional.


What not to do


Do not urinate on the sting, apply alcohol, ammonia or random homemade mixtures, or rub the area with sand. Do not break blisters or cover the skin tightly. These practices do not reliably neutralise venom and may worsen irritation or nematocyst discharge.


When it is an emergency


Difficulty breathing, chest pain, widespread swelling, hoarseness, fainting, confusion, marked weakness or rapid deterioration require an immediate emergency call. Medical assessment is also needed when a large area is affected, the sting involves the face, eyes, mouth or throat, pain does not improve, or the person is a young child, an older adult or has a history of severe allergic reactions. https://healthpont.com/jellyfish-stings-what-should-you-do-and-which-home-remedies-may-cause-harm/