How should I treat a jellyfish sting?

If someone gets stung by a jellyfish, the first thing to do is assess the severity of the sting. If the person appears to be having a severe or systemic reaction, seek immediate emergency help.

If the person is not having a severe reaction, know that most jellyfish stings can be treated by home remedies. First, remove any pieces of tentacle still on the skin by washing with seawater and scraping gently with a credit card or similar hard surface (not your hands or a towel, which can cause the discharge of more venom). Deactivate most stingers by generously rinsing with vinegar for at least 30 seconds.

Sea nettles and Portuguese man-of-war stingers may be deactivated using a paste of baking soda and seawater. For relief of pain or irritation after the sting is treated, try soaking in tolerably hot water for 20 minutes. Calamine lotion or lidocaine ointment may relieve some itching and pain.
Dr. Michael Roizen, MD
Internal Medicine
For stings from most North American and Hawaiian jellyfish, remove the tentacles and rinse the area with hot water for relief. No hot water available? Seawater will work. Then apply a topical anesthetic such as benzocaine or lidocaine.
Dr. Jack Merendino, MD
Endocrinology Diabetes & Metabolism
If someone is stung by a jellyfish, they should follow these steps. Do not immerse the wound in cool freshwater or rub vigorously --  both could cause the cysts to fire and cause more pain.
  1. Remove the tentacles -- try brushing off with an object (such as a credit card) combined with shaving cream. You can also use seawater to rinse off the tentacles.
  2. Once the tentacles and cysts are removed, immerse the affected area in hot water (104-113F, or as hot as you can tolerate) for approximately 20 minutes. This strategy is better than using vinegar, urine, or other therapies. 

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.