At the seaside, jellyfish stings are not uncommon. In mainland France, they are most often not serious. However, in warmer seas or in cases of severe poisoning, they can cause discomfort and require you to consult a doctor quickly. Here is what you should and should not do in the event of a sting.

HOW CAN A JELLYFISH STING ME?

Jellyfish, of which there are more than 1,500 species, are planktonic. Gelatinous and transparent in appearance, jellyfish have no skeleton, no lungs, no blood, and not even a real brain. They consist of a cap, called an "umbrella" and tentacles covered with mini-suction cups containing cells (nematocysts), which release their venom when they come into contact with a body (for example, your skin).

WHAT WILL I FEEL IF A JELLYFISH STINGS ME?

At the time of the sting you will feel a sharp pain, like an electric shock or a burn. For 30 to 40 minutes, you will have more and more pain. You may even feel tingling (paresthesia) in the area of ​​the sting. In about ten minutes, the skin will redden, then a red-brown or purplish rash may appear as if you had received a whiplash or multiple small stings. The extent of these marks gives an indication of the surface area of ​​the skin concerned. It is not impossible, but rare, that you will have a vagal malaise following the sting, resulting in the sensation that you are going to lose consciousness.

CAN I HAVE OTHER SIGNS, OTHER THAN ON MY SKIN?

Most of the time the effects of jellyfish stings contracted on the French coasts are limited to the skin. In case of severe envenomation and/or if you are allergic, you may feel unwell, have headaches, a racing heart or feel dizzy. Consult the lifeguards on site or a doctor.

In warmer seas, such as in the Antilles (due to the Alatina alata jellyfish in particular), in the south of the United States or in Australia, some species of jellyfish are more dangerous. From 30 minutes to 4 hours after the sting, headaches, dizziness, vomiting, muscle spasms, convulsions, sometimes even fainting, as well as cardiac and respiratory problems (Irukandji Syndrome) may appear. If such symptoms appear, you must call for help and go immediately to the emergency room of the nearest hospital.

A Guadeloupe study showed that the vast majority of Irukandji syndromes occurred between June and September from the 22nd to the 26th day of the moon.

When you arrive at your holiday resort, find out which days the risk is highest.

WHAT SHOULD I DO IF I GET STUNNED BY A JELLYFISH?

• First of all, stay calm, don't panic and especially don't rub the sting site. In fact, very few nematocysts release their venom straight away and transparent tentacles remain attached to the skin. If you rub them, they will release their toxin.
• Carefully remove the visible tentacles with tweezers (after putting on gloves to protect your hands).
• Then apply sand (shaving foam is ideal) to trap the invisible jellyfish debris that you will remove by gently scraping the sand or foam with a stiff cardboard.
• Then rinse the wound thoroughly for several minutes with sea water (or salt water), fresh water would burst the few remaining nematocysts.
• The venom is sensitive to heat, so you can use hot salt water or approach a heat source (without burning yourself!). Vinegar can be used for some species and not for others. Ask the locals if it is indicated.
• Then apply cold by protecting the skin with cloth between the skin and the ice cubes, can calm the unpleasant sensations (burning, pain).
• Once the wound has been well cleaned, you can apply an antiseptic.
• If the pain persists or if you have general symptoms, consult a doctor.
• If you are not up to date with your tetanus vaccination, get vaccinated.
• Finally, if you get bitten in a tropical region, the risk of general symptoms is greater, it is better to consult a doctor and get yourself monitored.

A FRIEND ADVISES ME TO MAKE THE WOUND BLEED, SHOULD I LISTEN TO HIM?

Stick to the advice given above. There are many misconceptions about jellyfish stings; they are often useless and sometimes dangerous. You should never suck the wound and suck out the venom with your mouth, or make the wound bleed. You should also never urinate on the wound, which could become infected.

AM I AT RISK OF HAVING A SCAR?

Most often, the lesions disappear in 3 to 10 days without leaving any traces. But sometimes a pigmented or thickened scar (keloid) can appear and persist for several months or years; this happens when the contact with the jellyfish was long or the poisoning was severe.