Jellyfish at the beach: how do you avoid them and what do you do if you're stung?

When and where are they most common?

Jellyfish are more common in late summer and in warm seas, but their arrival depends above all on currents and wind. A wind blowing from the open sea towards the beach (onshore) can bring a whole swarm to the shore in a matter of hours. You'll come across more of them:

• in calm, warm water, often in the afternoon;
• after several days of sustained onshore wind;
• near areas where currents concentrate them, along a front or a line of foam;
• during certain seasonal blooms, which vary from one year to the next.

A jellyfish-free day can turn into a jellyfish day simply because the wind has shifted. Relying on yesterday isn't enough: it's the situation right now that counts.

How to avoid them

A few habits noticeably reduce the risk:

• Ask locals, beach clubs and lifeguard stations whether there are any around at the moment.
• Check the strandline and the surface before going in: stranded jellyfish often signal a swarm offshore.
• Avoid swimming just after a strong onshore wind.
• Consider wearing a lycra top, a rashguard or a wetsuit if you're sensitive: covered skin gets stung far less.
• Stay near the shore and watch the children, who are more exposed.

The condition reports shared by the BeachFinder community can also flag an unusual presence at a given spot.

The right steps if you're stung

Stay calm and work through it in order:

• Rinse generously with seawater, never with fresh water: fresh water bursts any stinging cells still present and intensifies the pain.
• Remove the tentacles left on the skin by gently scraping them off with a rigid card (bank card, the back of a knife), without rubbing with bare hands.
• Apply heat: hot water, as hot as you can bear (around 40-45 °C), for several minutes, helps neutralise the venom and ease the pain.
• Don't scrub the area with sand and don't scratch it.

Myths to forget

The most widespread belief is wrong: urinating on a sting does nothing and can even make things worse. Likewise, rinsing with fresh tap water, applying ice directly to the skin or scrubbing with sand are counterproductive steps that set off more stinging cells.

Vinegar is sometimes recommended for certain tropical species, but it can worsen the sting of other jellyfish found on our coasts: when in doubt, stick to seawater and heat. Finally, a stranded and even dead jellyfish can still sting: don't touch it with bare hands.

Recognising the main jellyfish

Not all jellyfish are the same. On French coasts, the ones you'll most often come across are:

• The mauve stinger (pélagie) in the Mediterranean: small, purple, stinging, responsible for the majority of summer stings.
• The barrel jellyfish (rhizostome): large, white with a blue-purple rim, barely stinging at all.
• The moon jellyfish (aurélie): translucent with four rings, virtually harmless.
• The Portuguese man o' war (physalie), more on the Atlantic side: it's not a true jellyfish, but its sting is very painful; on contact, heat is still useful and medical advice is recommended.

If you're unsure of the species, apply the general rule: seawater, remove the tentacles, heat, and keep an eye out.

When to see a doctor

Most stings stay mild and ease within a few hours. Seek help quickly, or call the emergency services, if the following appear:

• a whole-body reaction: difficulty breathing, swelling of the face or throat, faintness, nausea, palpitations;
• an extensive sting or one on a sensitive area (face, eyes, mouth, genitals);
• intense pain that won't ease, or a wound that becomes infected over the following days;
• a sting in a young child or a vulnerable person.

If in serious doubt, don't stay alone and alert the emergency services. In France, 15 (SAMU) and 112 (the European emergency number) can be reached free of charge.