So, what do you do when you're with somebody who gets a jellyfish sting? Number one, stay calm. Number two, get them out of the water, and get yourself out of the water. Stay safe. If you get stung, you're not going to be able to help your friend who being stung as well. Rinse off the tentacles. They'll be stuck to the person's legs. Saltwater is best. Warm water. Fresh water can make the sting even worse. Peel off any remaining tentacles. Use tweezers or something else. Don't use your own hands because you'll get stung. You can still get stung after the tentacle has been unattached from the jellyfish. You can use over the counter medications to help with the pain. You can use ice packs to help with the pain. If it looks like it's an allergic reaction, if the person is having trouble breathing, gets hives, has wheezing, shortness of breath, call a doctor right away. Call 911. If the welts are more than half the size of your arm or your leg, or about that size. A big size like that. Call your doctor for some help.