Get out of the water immediately
Call emergency services if the person has trouble breathing, chest pain, fainting, or severe swelling
Rinse the sting area with vinegar for at least 30 seconds if available
Remove visible tentacles with tweezers or gloved hands
If vinegar is not available, rinse with seawater
Do not rinse with fresh water
Do not rub the area
Do not use bare hands to remove tentacles
Immerse the area in hot water, 104–113°F, for 20–45 minutes if tolerated
Use a hot pack if hot water is not available
Take an over-the-counter pain reliever if needed
Apply a topical hydrocortisone cream or antihistamine cream for itching if appropriate
Seek medical care if pain is severe, the sting is on the face or genitals, or symptoms worsen
Watch for signs of allergic reaction or infection
Avoid scratching the sting area