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Medicine for the Outdoors

Dr. Paul Auerbach is the world's leading outdoor health expert. His blog offers tips on outdoor safety and advice on how to handle wilderness emergencies.

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Sea Bather’s Eruption

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From the month of May through September, oceangoers along the U.S. Gulf coast need to be concerned about a particular form of skin rash caused by tiny jellyfish. As the summer season progresses, this can also become a problem along the entire eastern seaboard. I've been afflicted while scuba diving in Cozumel, Mexico, and the episodes can be much more than a minor annoyance. Indeed, the intensity with which some people react to these particular stings was an impetus for the development of Safe Sea, a jellyfish sting inhibitor product for which I participated in the design of clinical trials.

Sea bather’s eruption, often misnamed "sea lice" (which are true crustacean parasites upon fish), occurs in seawater and more often involves bathing-suit-covered areas of the skin, rather than exposed areas. The skin rash distribution is very similar to that from seaweed dermatitis, but no seaweed is found on the skin. The cause is stings from the nematocysts (stinging cells) of thimble jellyfish, such as Linuche unguiculata, and the larval forms of certain anemones. The victim may notice a tingling sensation under the bathing suit (breasts, groin, cuffs of wet suits) while still in the water, which is made much worse if he takes a freshwater rinse (shower) while still wearing the suit. The rash usually consists of red bumps, which may become dense and confluent. Itching is severe and may become painful.

Treatment is often not optimal, because application of vinegar or rubbing alcohol to stop the envenomation may not be very effective. An agent that may work better is a solution of papain (such as unseasoned meat tenderizer), which may be applied using a mildly abrasive pad, although a good outcome is not guaranteed. After the decontamination with any agent and a thorough freshwater rinse, apply hydrocortisone lotion 1% twice a day to treat the inflammatory component of the skin reaction. If the reaction is severe, the victim may suffer from headache, fever, chills, weakness, vomiting, itchy eyes, and burning on urination, and should be treated with oral prednisone as if he suffered from poison oak. Topical calamine lotion with 1% menthol may be soothing.

Prevention is obviously quite important. If you are able to obtain the product, cover exposed skin areas with Safe Sea. This includes at least a few inches underneath the cuffs of wet suits or Lycra-type "stinger suits" that are equipped with elastic cuffs at the wrists and ankles, and sometimes around the neck. If you only wear a normal bathing suit, which does not have tight cuffs, the tiny creatures can easily wash onto your skin underneath the suit, where they can wreak havoc. So, if you are concerned about the possibility of seabather's eruption, you must also apply the Safe Sea underneath your bathing suit. If there are "thimbles" (jellyfish) visible in the water, it is best to stay out. If you are swimming in apparently uninfested water and begin to feel a tingling sensation on your skin, then the "swarm" may be moving into your location and you should exit the ocean.

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Tags: In the Water

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About the Author

Dr. Paul S. Auerbach is the world’s leading authority on wilderness medicine.

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