Bored Review – Is that really a Jellyfish?!

You decide to spend your elective month in Bora Bora hoping you’ll pick up a clinical pearl or two on trauma and envenomation from marine fauna. One morning on your day off from the hospital, you decide to get up early and run on the beach. Reaching “flow” at the end of your run, you are feeling happy, delirious, and invincible at the same time, and think not one thing in the world could affect your mood. You decide to lay down in the sand and make a sand angel to leave your mark and let other people know how amazing you are feeling. All of a sudden, you feel this horrible pain in your leg, and you pop up and see a Box Jellyfish lying underneath you, buried in the sand. You look down and see a red area on your leg with white blotches and welts starting to form. You scream!

What are some different types of jellyfish and where are they found?

Box Jellyfish (aka “sea wasp”): Australia, Hawaii, and Florida 

Portuguese man-o-war: Atlantic, Indian, and Pacific Oceans

Lion’s Mane Jellyfish: Cold waters of the Artic, Northern Atlantic, and Northern Pacific 

What does a jellyfish sting look like?
Linear strings of erythema or “string of pearls” in a whip-like pattern

Severe case:

What is the pathophysiology of a jellyfish sting?
-A tentacle attaches or touches skin. Through a unique delivery mechanism, nematocysts discharge and lead to entry of venom into host.

What are nematocysts?
Large specialized cells used for prey capture and defense that are discharged in response to a chemical or mechanical stimulus. When stimulated, nematocysts discharge, releasing a barbed device that penetrates the skin to deliver venom into a target creature (AKA you, who was previously so happy on the Bora Bora beach).


How do you initially treat a jellyfish sting?

  • If still attached, remove tentacles with a glove or towel, taking care as to not cause further nematocysts from firing and releasing venom.

  • Monitor for systemic symptoms (tachycardia, hypertension, agitation, cardiogenic shock, pulmonary edema–in rare and very severe cases). 

  • Blot area (can use adhesive tape if available). 

  • Irrigate with warm normal saline (or seawater can be used in place of NS) OR apply 5% acetic acid (vinegar) topically to deactivate the nematocysts that have not discharged into the skin and to prevent further venom from being released. Dip an injured limb or soak a towel and wrap the injured trunk. 

  • Some studies indicate that hot water (or warm saline) and topical lidocaine or benzocaine may be more beneficial at relieving the pain of jellyfish stings than vinegar. Topical lidocaine can also deactivate nematocysts (exception: Box Jellyfish stings are better treated with vinegar).

  • Antivenom to the Box Jellyfish exists in Australia and is given for severe, systemic cases

What additional treatments may be indicated?
-Apply topical antihistamine or corticosteroid cream for itching. Observe for development of systemic symptoms. Provide supportive care.

What treatments should you avoid?
Do not apply freshwater or urine, as they are hypotonic solutions and may cause more nematocysts to fire and envenomate.

Summary of treatment goals:

  • Alleviate local effects of venom, and prevent further nematocyst discharges

  • Prevent systemic symptoms including diarrhea, swelling lymph nodes, muscle spasms, coma, shock, and death 

Spending the day in the ED on your day off wasn’t what you’d imagined, but you‘re glad you are now equipped to handle jellyfish stings (You decide it was a good idea not to mention that you peed on your sting before calling EMS). 




Special thanks to Dr. Silverberg and Kylie Birnbaum


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PGY2 clinical monster in training/EMIM resident/improviser

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