On the tentacles of a jellyfish venomonous cells are located. When being touched, jellyfish inject these cells containing venom into the victim. Depending on the type of jellyfish and the victim's sensitivity, the pain can be less or more severe. Usually being stung by jellyfish on our coast is not dangerous or mortal.
When you have been stung, carefully remove any parts of tentacles which may have been left on the skin. Do this by rinsing the wound with salt water (not fresh water). Avoid rubbing the wound! Rinsing with salt water or applying a cold compress may help to relieve the pain. In case of severe discomfort, painkillers may prove necessary.
Take care: even beached and dying jellyfish can still sting when touched!
Read more on jellyfish
Thanks to Francis Kerckhof, RBIN/OD Nature