We can not do anything to protect ourselves from jellyfish. False.

First, we avoid bathing when jellyfish beds squat the seaside.
A new "jellyfish weather" service has just been launched in the PACA region: Jellyfish , which gives 5 color indices according to the alert level (from red, the risk is high, to blue, the risk is almost nil ).
Otherwise, we wear a finer wetsuit than a diving model, seen straight from Australia, which makes it possible to dodge the jellyfish sting and filters the UV (55 € on S tingersuit).

First, rinse the jellyfish sting with fresh water. False.

It must be rinsed with seawater, otherwise there is a risk of bursting micro-bubbles of venom and accentuate the burning sensation . Needless to suck the venom or rub the sting by hand (or sand, as we sometimes hear ).

We can pee on it immediately. True.

Simply because the venom is "thermolabile", that is, it reacts to heat.
But, besides the fact that it is not always possible, one should not suffer from urinary infection so as not to over-infect the area. Otherwise, approaching a lit cigarette from the jellyfish sting, is also effective.

The tentacles are scraped. True.

With a blue card or a postcard ... after putting shaving cream on it . The idea is to gently leave small invisible filaments stuck to the skin without irritating it more. We can, beforehand, use a tweezers to remove the most visible.
But, distrust: the fragments can still sting. Once the area cleared of any residues, disinfect the antiseptic spray.
And if swelling occurs, it is better to consult to rule out the path of an allergic reaction to the jellyfish sting.

Thanks to Dr. Loïc Etienne, emergency doctor.