DAN Medical Frequently Asked Questions

Back to Medical FAQ List

Seaweed Dermatitis

What's the difference between Sea Bather's Eruption and Seaweed Dermatitis?

Sea bather's eruption is easy to confuse with "seaweed dermatitis." There are more than 3,000 species of algae, which range in size from 1 micron to 100 meters in length. The blue-green algae, Microcoleus lyngbyaceus, is a fine, hairlike plant that gets inside the bathing suit of the unwary aquanaut in Hawaii and Florida waters, particularly during the summer months.
Usually, skin under the suit remains in moist contact with the algae (the other skin dries or is rinsed off), and becomes red and itchy, with occasional blistering and / or weeping. The reaction may start a few minutes to a few hours after the victim leaves the water.

The Treatment

Treatment consists of a vigorous soap-and-water scrub, followed by a rinse with isopropyl (rubbing) alcohol. Apply 1 percent hydrocortisone lotion twice a day. If the reaction is severe, oral prednisone may be administered.

For more information on marine life injuries, see the complete article by Paul S. Auerbach, M.D., M.S. on Marine Life Trauma from the Jan/Feb 1998 issue of Alert Diver.