You've been stung by a jellyfish. Rule N° 1, Don't pee on it! And possibly all other so-called treatments you've read about will serve to make matters worse as well. You've been told the ammonia or whatever in your pee counteracts the sting. These old wives' tales are mostly 'Tommyrot'! After testing many so-called solutions, researchers at the University of Hawaii found only one which was effective. You should soak the infected skin in strong vinegar. This is the only cure that will very effectively neutralize the jellyfish 'harpoons'. After a good soaking of vinegar, you still have to carefully take the stingers out using tweezers, or preferably have a friend do it for you.
A jellyfish sting is like a thousand tiny harpoons, injecting you with venom. If the jellyfish that stings you is a box jellyfish, which is found in warm coastal waters around the world, its venom is deadly. The most lethal varieties are in the Indo-Pacific region and northern Australian waters. The Australian box jellyfish (Chironex fleckeri), is considered to be the most venomous marine animal, and you will probably die within two minutes in the absence of the administration of the one and only antidote.
When you search on Google for an answer to the question, “What to do if I’m stung by a jellyfish?”, you will receive conflicting responses. Some recommend rinsing with seawater, then scraping off the tentacles, then spraying with vinegar or showering with very hot water. Others seem to be confused about the sequence of these measures, but justify almost all potential remedies, not always in the same order. No one seems fully aware of the right answer. Only the results of actual scientific studies are far more reliable.
Whatever you do, don't attempt to scrape the tentacles off. Jellyfish spiked sacs are activated in part by pressure. The slightest compression on a stinger stimulates it to release more toxins. Yes, it will result in fewer spears piercing into your skin than pulling the spears out with tweezers, but the additional venom will increase the stinging sensation, and in the case of certain species, possibly kill you. Scraping off its tentacles can make the difference between needing pain relievers or a visit to your own funeral. So even if you're stung by a less deadly jellyfish, you most certainly shouldn't attempt to do other than remove the tentacles with tweezers, otherwise you'll end up with more venom in your body and more pain. That is something you must avoid at all costs.
As stated before, soak the infected skin, together with the tentacles, in the most concentrated vinegar you can obtain. That is to say, with the highest pH. The highest is normally apple cider vinegar with a pH of between 3.3 and 3.5. Vinegar inactivates the jellyfish’s nematocysts so they can’t be triggered, but you must still remove the tentacles with your tweezers, thus not ending up with more venom than when you started.
Alcohol, even beer, will instantly trigger the nematocysts, and they'll zip into your flesh like arrows from the English longbow at the Battle of Agincourt. Yes, I know the sting is throbbing. Just resist any scratching.
Washing the sting with seawater is inoffensive, but I'm sorry to tell you, you might wash the tentacles to other parts of the body, only to attach themselves elsewhere. Products like shaving cream or baking soda, which have been bandied around, are virtually of no earthly use.
Now for the good news. There now exists a pretty effective product currently being marketed in the form of a spray to treat jellyfish stings called StingNoMore, and which you can see at stingnomore.com. Of course, it contains vinegar to inactivate the nematocysts, and urea, that dissolves the glop which helps the tentacles attach to the skin. So any tentacles will be washed away rather than you having to take them our with tweezers. Speaking of urea, human pee is too wishy-washy, just not concentrated enough, and may contain sufficient salt to enable the nematocysts to whack in more venom.
After using the vinegar and tweezers, you should bring heat to bear where you have the sting. So not a cold pack as you might imagine, but apply heat. This will effectively reduce the ferocity of the venom It is quite natural to believe ice will cool the burning wound, but heat actually lessens the effectiveness of the venom. In fact, an ice pack will double the size of the injured area.
So the next time you’re off on holiday to the beach, don't forget your tweezers and bottle of apple cider vinegar (if you’re not stung, you can always use it to make salad dressing)! Otherwise, you'll have to wear pantyhose or maybe an Islamic Burkini (Muslim bathing suit)—the smooth mesh protects against many stinging species. Sure, you’ll look like a fruit and nut case, but you won't be stung!