Every year near to everybody on the Philippines hit it. Burns by Jellyfish or dead parts of their tentacles who feel at contact like a lash. Often caused by the notorious Box Jellyfish who is especially in the Philippines common and the wounds causes. Where the burns when they occur always have to be treated.
But here I have to say that I’m no Doctor and the most tips are from Natives, but I used them already often with success. The most important is what everybody first makes a mistake. Don’t rub the affected area with sand! Because remaining parts of the jellyfish wreak further damage.
The Filipinos deal with these jellyfish burns easily with vinegar. This should be in every hotel always in stock. Otherwise, simply send someone to order vinegar. Then simply rinse the affected area with it. But here you should be a little careful, before you start to rub the rest parts away, because it takes a few seconds until the remaining threads do no harm. Everybody who get dizziness or something like that should be brought immediately to a hospital, because there can be an allergic shock.
So that you don’t have problems in the next days you should eat food without protein. That means particularly Shrimps, Lobster, Fish and everything with chicken. So that no everybody gets in panic about these near to invisible Jellyfish Parts I must also give a clear signal. In the last 3 years I have only 2 times a problem with them, but every time I never see something in the water. So you can’t protect yourself and the Jellyfish you can see without problems are not dangerous.