Just in time for summer, researchers say an over-the-counter lotion sold as a jellyfish repellant does indeed seem to render the beachgoer’s nemesis powerless - usually.

In a study that exposed two dozen volunteers’ arms to jellyfish tentacles, researchers found that the lotion kept all but one arm from becoming red and swollen. And only a few participants felt discomfort in the lotion-protected arm.

The product, called Safe Sea, was developed in Israel several years ago and has been available there and in the U.S., Japan and a number of other countries.

There have been no published studies on its effectiveness until now, however, according to lead author Dr. Alexa Boer Kimball of the Stanford University School of Medicine in California.

She and her colleagues report their findings in the June issue of the journal Wilderness and Environmental Medicine. One co-author is with Nidaria Technology, the Israeli company that markets Safe Sea, and another serves as a consultant to the company.

Scientists created the sting-inhibiting lotion using compounds designed to mimic the defensive secretions of the clown fish, a creature that swims through life immune to the stings of the sea anemone. It is currently marketed as a stand-alone sting inhibitor and as a combination product that include a sunscreen-the version tested in the current study.

Kimball and her colleagues exposed 12 adults to the tentacles of the sea nettle, a type of jellyfish commonly found along the U.S. coast, in places like Florida, the Chesapeake Bay in Maryland, and in a large area of the Pacific.

Another 12 volunteers endured the tentacles of the box jellyfish, a creature with a particularly nasty sting that can even be life-threatening in some cases. It’s found in the Gulf of Mexico area, and along the coasts of Florida and Texas, according to the study authors.

Each volunteer had one arm coated with the inhibitor lotion and the other arm with regular sunscreen before having the tentacles placed on them.

Kimball’s team found that none of the inhibitor-treated arms showed signs of irritation after tangling with the sea nettle tentacles, while all of the arms shielded with only sunscreen developed a rash. Two people complained of “minimal discomfort” in the treated arm, while all said the sunscreen-only arm was painful, the researchers report.

In the box jellyfish group, one treated arm showed a skin reaction, and three volunteers reported discomfort in their inhibitor-shielded arms.

Kimball said the anti-sting lotion can “provide some real protection” to people whose jobs regularly take them into the water.

“For recreational swimmers, surfers and divers, who should be wearing sunscreen anyway,” she noted, “this provides additional protection in case they run into jellyfish while they are in the ocean.”

SOURCE: Wilderness and Environmental Medicine, June 2004.