An intensely itchy rash due to contact with the tiny thimble jellyfish (Linuche unguiculata). The reaction tends to start 4-24 hours after exposure to the jellyfish. People who have had previous exposure to seabather's rash may have an immediate stinging sensation. Some people feel like they have the flu with nausea, vomiting , headache, muscle and joint aches, and malaise. Other names for this condition include bather's eruption, sea poisoning, and seabather's itch and the jellyfish are sometimes called sea critters or, incorrectly, sea lice.