Jellyfish Envenomation

Jellyfish EnvenomationSummer is officially in full swing and we all love it! Well, my kids do get tired of hearing about all of the potential hazards that lurk around every corner, but I just have a hard time turning that part of my brain off. I mean, someone has to anticipate the Fish Hook FBs, Vehicular Hyperthermia, and Heat Related Injuries, right? Of course someone also needs to be paying attention to the water related dangers as well (ex, Submersion Injury Prevention, C-Spine Injury and Submersions) and that brings to mind all of the crazy sea creatures that want to cause us pain. Let’s take a minute to digest a Morsel of info on Jellyfish Envenomations:


Jellyfish: Basics

  • Jellyfish (belong to Cnidaria) sting via microscopic cnidae
    • Contain nematocysts – sharp, coiled tubes surrounded by venom
    • Can penetrate through surgical gloves [Balhara, 2014]
  • Stings typically occur: [Ping, 2011]
    • During the warm months (of course… that’s when humans go to Jellyfish environs)
    • To visitors/vacationers (because they aren’t familiar with the native hazards)
  • Cnidaria include 4 classes that contain 10,000 species. [Balhara, 2014]
    • >100 species are known to be dangerous to humans.
    • Classes:
      • Anthozoa
        • includes anemone and coral
      • Cubozoa
        • Box Jellyfish: may be the world’s most venomous animal; resides in Indo-Pacific (around Australia, ‘cause all horrifically poisonous animals live around Australia).
        • Irukandji Jellyfish: venom can cause catecholamine release and Irujandji Syndrome; also around Australia
      • Hydrozoa
        • Portuguese Man-of-War: found around the world; very long tentacles (~30 meters); nematocysts remain active for months after being washed up on shoreline; venom causes hemolysis
        • Blue Bottle Jellyfish: found around Australia; tentacles ~15 meters
      • Scyphozoa
        • Considered “true jellyfish.”
        • Sea Nettles
        • Large Hair Jellyfish


Jellyfish Envenomation: Symptoms

  • Most jellyfish envenomations are self-limited, local, nuisances. [Balhara, 2014; Sando, 2010]
    • Superficial pain and itch.
    • Skin irritation
      • Wheals and uritcaria
      • Vesicles and blistering (necrosis has occurred)
      • May persist for days
  • Can develop systemic reactions (especially, the more deadly jellyfish)
    • Nausea / vomitting
    • Malaise and myalgias
    • Headaches
    • Syncope and Dysrhythmias
    • Anaphlyactic like reactions
    • Hypotension
    • Respiratory failure (can occur within minutes)
  • Any structure that comes in contact with nematocysts can be affected (ex, Corneal Injuries) [Sonmez,2008]
  • Irukandji Syndrome [Balhara, 2014; Sando, 2010]
    • Can be caused by other jellyfish other than Irukandji, so can occur in the US waters also (not just an Australian issue). [Sando, 2010]
    • Severe systemic reaction that occurs within 30 minutes
    • Severe pain in head, truck and limbs
    • Sweating, piloerection, agitation/anxiety (catecholamine release)
    • Tachycardia and HYPERtension
    • Muscle spasms in the back and abdomen
    • Can lead to pulmonary edema and intracerebral hemorrhage


Jellyfish Envenomation: Management

  • There are no standard, consensus management strategies [Isbister, 2017; Balhara, 2014; Ping, 2011]
    • There is conflicting evidence, but this may be due to different species used in testing.
    • Alcohol, urine, or sand are NOT good options (so don’t pee on your friend!).
    • Below is a reasonable starting approach, understanding that tactics may need to be adjusted based on specific situations.
  • First things first:
    • Get person out of the water! Pain and panic while swimming are not a good combination.
    • Protect yourself! Nematocysts that have not been discharged can still fire, and can injure the rescuer.
    • Attend to airway, breathing, and circulation stabilization when needed (goes without saying really).
  • Deactivate the unfired nematocysts 
    • Do not rub the affected area as this may discharge more nematocysts.
    • Household vinegar (4-6% acetic acid) has been widely used.
    • Baking Soda slurry may also be applied.
    • Meat-tenderizer (papain) may hydrolyze the protein and inactivate.
  • Remove tentacles
    • Carefully… use a blunt object to scrap them off.
    • Wear thick gloves
  • Denature injected toxin / Treat the pain
    • Hot water immersion [Nomura, 2002]
      • Cubozoan venoms are heat-labile (inactivated by temps >43 degrees C)
      • Hot water shower treatment (20-30 min) is often noted to lead to improved symptoms. [Nomura, 2002]
      • Hot compresses can also be used on the scene. [Ping, 2011]
    • Cold packs [Isbister, 2017]
    • Oral or parenteral analgesia can also be provided based on severity of pain.
  • Anticipate problems
    • Allergic reactions have been known to occur
    • Irukanji Syndrome? Place on cardiac monitors, treat HTN (perhaps with Magnesium), treat pain.
  • Treat Symptoms
    • Using symptomatic therapies like anti-histamines is reasonable.
    • Antivenom does exist for the Box Jellyfish, but rarely used/needed.
    • THE MAJORITY CAN BE TREATED on the scene and don’t need to be transported to Emergency Departments. [Ping, 2011]


Moral of the Morsel

  • Being prepared doesn’t mean you’re paranoid. If your going to the beach, throw some vinegar in the trunk of the car.
  • A dead jellyfish doesn’t equal a safe jellyfish. The tentacles can still sting after being detached from the jellyfish’s body even.
  • Deactivate, Decontaminate, and Denature, but protect yourself also!
  • Hot Water Shower over Morphine! Instead of pumping in a bunch of opiates, find a shower… unless you have to attend to the ABC’s of lifesaving.



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Glatstein M1, Adir D, Galil B, Scolnik D, Rimon A, Pivko-Levy D, Hoyte C. Pediatric jellyfish envenomation in the Mediterranean Sea. Eur J Emerg Med. 2017 Jun 20. PMID: 28639958. [PubMed] [Read by QxMD]

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Sean M. Fox
Sean M. Fox
Articles: 583


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