To help reduce the pain, you can put calamine lotion or hydrocortisone cream on a jellyfish sting. You can also use an ice pack or hot water to help with the pain and swelling.
Wash the sting with clean water 2 times a day. Don't use hydrogen peroxide or alcohol, which can slow healing. You may cover the area with a thin layer of petroleum jelly, such as Vaseline, and a nonstick bandage. Apply more petroleum jelly and replace the bandage as needed.
Apply shaving cream. After you've been stung, the jellyfish stinging cells can continue to cause pain if you activate them. When you apply shaving cream, the jellyfish cells release the painful stinging chemicals into the cream. You then carefully scrape off the cream using something hard like a credit card.
Apply vitamin E or aloe vera juice to heal tissue and reduce inflammation.
Stop the Stinging
Strong reactions can see a fever, dizziness, nausea and cramps. Rinse the area with vinegar for at least 30 seconds. Remove tentacles with a pair of tweezers. After you remove the tentacles, soak the affected area in hot water (104-113 F or 40-45 C) for at least 20 minutes.
Heat is the key
“And if you Google it, many sites —even those considered reputable—will tell you to put ice on a sting to dull the pain. But research to date has shown that all marine venoms are highly heat sensitive, thus hot water or hot packs should be more effective than cold packs or ice.”
Vinegar inactivates the jelly's nematocysts so they can't fire, which means they won't be able to hurt you any worse. Once you treat the injury with vinegar, you'll still have to remove the stingers with tweezers.
Rinse the area with vinegar, for at least 30 seconds. If you don't have vinegar, use sea water.
Pour vinegar on the jellyfish stings for 30 seconds. This stops any tentacles (nematocysts) that haven't already fired venom from firing. If vinegar is not available, wash the stings with sea water.
A delayed reaction can occur many times over the course of 1 to 2 months following a sting. You may have a fever, weakness, or joint stiffness or swelling. Medical treatment may ease the discomfort and prevent complications from a delayed reaction.
Treat itching with an over-the-counter anti-itch cream and/or an antihistamine, such as diphenhydramine (Benadryl®). If itching is severe, see a doctor for a stronger preparation. See a doctor if someone is stung in the mouth, in or near the eye, on a large area of skin, or on the genital region.
What should you do if a jellyfish stings you? Scientists have found that applying vinegar is the best solution, and that popular remedies including urine, lemon juice, and shaving foam could make the situation worse.
Most jellyfish stings get better over a few days or weeks with home treatment. Severe reactions likely need emergency medical care.
If you are stung by a jellyfish, you should:
Soak the skin in hot water. Avoid cold water.
Soothe a jellyfish sting
The exact healing capabilities of Coca-Cola on jellyfish stings remains a topic of debate but according to an Australian study from 1993, Coca-Cola reduced the pain and the reaction to a sting between 25 to 75 percent.
Often, it's best to rinse a sting with vinegar. Vinegar is a weak acid that might keep the stingers from firing for some kinds of stings (especially from dangerous types like box jellyfish). Do not rinse with fresh water (like tap or bottled water) because that can make more stingers fire.
Irukandji jellyfish's stings are so severe they can cause fatal brain hemorrhages and on average send 50-100 people to the hospital annually. Robert Drewe describes the sting as "100 times as potent as that of a cobra and 1,000 times stronger than a tarantula's".
Rinse with salt water.
Rinsing the area gently in salt water will help remove any lingering bits of tentacle to help prevent additional stings. And make sure it's salt water, not fresh, because any change in the salt balance around the nematocyst will encourage it to fire and can actually make the stinging feel worse.
Researching the Portuguese man o' war jellyfish, the study found that popular treatments such as lemon juice, urine and baking soda could actually make stings worse. The best antidote is, in fact, vinegar.
Put WINDEX on ice & take it to the beach (does not help if you leave it at home or back in the car) Spray down affected area -it"ll take the sting right out!"
One of the main causes of this discomfort is a type of protein called a porin found in the venom of all jellyfish—and in all their relatives, including corals and anemones, which together form a group of creatures collectively known as cnidarians.
First-aid care
Use water that's 110 to 113 F (43 to 45 C). It should feel hot, not scalding. Keep the affected skin immersed or in a hot shower until the pain eases, which might be 20 to 45 minutes. Apply 0.5% to 1% hydrocortisone cream or ointment twice a day to the affected skin.
Hot water inactivates the jellyfish toxins and so stops the pain; it is effective in about 90% of cases after 20 minutes.