how to treat a jelly fish bite?

and then pee on it.
Its easier that way

Vinegar!

yeah
that will help

Onion

"Think 100 times before you take a decision, But once that decision is taken, stand by it as one man" - Muhammad Ali Jinnah

Sure it does, dweller.

Its true Blue_Rose You wont belive once i saw Qatari family on the beach. Their little son got bitten by jellyfish. They applied SOFT DRINK (Cola) on infected area and that little boy got OK! :|

"Think 100 times before you take a decision, But once that decision is taken, stand by it as one man" - Muhammad Ali Jinnah

yousri that is drink ..but u were taling abt onion?

Here's How:

1. Stay Safe. As always, safety is the most important step. Jellyfish tentacles (nematocysts) may still be on the skin. Follow universal precautions and wear personal protective equipment if available.

If the species is known to be box jellyfish (Chironex fleckeri) or Irukandji (Carukia barnesi), get emergency medical help immediately. For box jellyfish stings, vinegar may help (see tips).
2. Rinse the tentacles off. Rinse away the tentacles using hot water if possible (see step 5 for how hot). If heated water isn't available, use salt water rather than fresh. Fresh water may worsen the stinging pain.
3. Peel off the tentacles. Remove any remaining tentacles with a gloved hand, stick, shell or tweezers. Be careful not to get the tentacles on yourself or on clothing.
4. Watch for anaphylaxis. Anaphylaxis is a severe allergic reaction that can result in:
* itching
* hives
* shortness of breath
* wheezing
* tightening of the throat
* flushed skin
* weakness
* dizziness
Anaphylaxis can also cause a drop in blood pressure known as anaphylactic shock.
5. Immerse the stung area in hot water. How hot is hot? There isn't too much evidence that water under 102 degrees is going to help much, and a lot of evidence that water over 122 degrees is extremely effective. Since it's unlikely you'll have a way to truly gauge the temperature of water in a shower or a hot bath, the general rule is to have the victim either shower or immerse the sting in the hottest water he or she can stand. Work up to the heat and be careful not to scald (burn) the victim.
6. Ibuprofen and acetaminophen will help relieve pain. Ice or heat may also help. Mild itching may be helped with diphenhydramine.

Tips:

1. The Portuguese or Pacific man-of-war and the bluebottle are technically not jellyfish, but treatment is the same. Remove all tentacles from the sting site and rinse thoroughly, preferably with hot water. Watch for confusion, chest pain, and weakness. Always seek emergency medical treatment for these. Man-of-war stings can be very serious.

2. Urine will not work on a jellyfish sting. Some victims have reported pain relief, but urine does not always have enough acid to neutralize the venom. Use hot water.

3. Plain white distilled vinegar (acetic acid) like you would find in your kitchen has long been the standard first aid treatment for jellyfish stings. Its use has become controversial in the last few years and several studies leave us questioning whether vinegar really works. Vinegar is still recommended for use on box jellyfish stings, so if it's available, I'd give it a try.

Source:
http://firstaid.abou...

Drac... too much text...

Lets just stick to...

Phoenix_Rising and Dracula have it spot on. . .

I was stung across the face while scuba diving and it really does feel like a combination between electrocution and acid burn. It hurts a LOT.

Vinegar and hot water are the two methods that divers use; we generally carry vinegar in the boat with us as a first method of treatment. We use very hot water after that - it needs to be so hot that you can barely stand it, but not hot enough that it will burn/scald you.

Hopefully you won't get stung, though :(