Seabather's eruption


  • Cnidaria larvae get trapped, release toxin
  • Nematocysts of the larval forms of sea anemones: Edwardsiella lineata
  • Thimble jellyfish: Linuche unguiculata
  • Not be confused with cercarial dermatitis, which is caused by freshwater schistosomes or coastal water clam diggers

Clinical Features

Excoriated papules in areas covered by swimsuit. Box shows Linuche unguiculata, the thimble jellyfish, whose larvae and adult forms caused this dermatitis.
  • Rash generally under the garments worn by bathers and swimmers (where the organisms are trapped after the person leaves the water)

Differential Diagnosis

Marine toxins, envenomations, and bites

Travel-related skin conditions

See also domestic U.S. ectoparasites


  • Typically a clinical diagnosis


  • Thoroughly wash and dry bathing clothes.
  • Consider oral diphenhydramine for pruritis.


  • Discharge home
  • Return precautions for signs of bacterial superinfection of the lesions.

See Also

External Links