Healthy Travel -- When the sea bites back

Chrome 2001
Aetna Intelihealth InteliHealth Aetna Intelihealth Aetna Intelihealth
. .
Harvard Medical School
Chrome 2001
Chrome 2001

Healthy Travel -- When the sea bites back

Interactive Tools
Healthy Travel
Healthy Travel -- When the sea bites back
Healthy Travel -- When the sea bites back
Healthy Travel
InteliHealth Medical Content

Reviewed by the Faculty of Harvard Medical School

travel tips healthy tavel menu
When the Sea Bites Back

Jellyfish, Man-o-war

Jellyfish and Portuguese man-o-war are encountered frequently in warm ocean waters. Both have tentacles that can stick to the skin and will continue stinging even after they are broken off or the animal is dead.


Always rinse with salt water, not fresh, which can stimulate more stinging. If tentacles are still attached, do not rub them. Instead, cover them with sand and then scrape them off with a knife, sea shell, comb, credit card or similar object.

Once all the tentacles are detached, hot water can help relieve the pain. According to most sources, rinsing with white vinegar also helps. Do not apply meat tenderizer to the area of the sting! 

Caution: Just as with bee stings, some people will have an extreme allergic reaction to sea stings. Watch out for signs of anaphylactic shock, including extreme swelling, widespread rash, difficulty breathing, confusion, and sudden fainting. Seek medical help immediately if stings are severe or shock occurs.


Seabather's Eruption

Seabather's eruption, also known as "sea lice," can happen when a swimmer passes through a cloud of almost transparent larvae of certain jellyfish. When the larvae become trapped between the swimsuit and skin, they release their venom, which contains extremely irritating and allergy-producing enzymes and proteins. About 10,000 cases occur each year in the United States.


  • A prickling sensation while swimming in tropical seawater
  • Mild fever
  • Small, raised, red, painful sores all over the area where the bathing suit covered the body

Where and when:

  • South Florida and throughout the Caribbean
  • Peak season is March until August


  • Swim only in a swimming pool.
  • If you are going into the ocean, wear as little skin covering as possible, and no T-shirts.
  • If you feel stinging while swimming or diving, leave the water and remove your bathing suit as soon as possible.


  • Rinse with jellyfish-free sear water first. Then shower.
  • For the allergic reaction, apply 1% hydrocortisone lotion and/or take an oral antihistamine. In severe cases, an oral corticosteroid may be needed.
  • Throw out the swim suit you were wearing to avoid another eruption.
* Seabather's Eruption

pole regional info
Choose a region of the world:



Last updated June 20, 2014

    Print Printer-friendly format    
This website is certified by Health On the Net Foundation. Click to verify.