Seabather's Eruption

Updated: Oct 20, 2021
Author: Clarence W Brown, Jr, MD, JD, FAAD, FACMS; Chief Editor: William D James, MD 



Seabather's eruption was first described in 1949 as a pruritic papular eruption occurring in bathers off the eastern coast of Florida. Seabather's eruption is a highly pruritic, papular eruption that occurs underneath the swimsuit after extended exposure to seawater. Seabather's eruption results from a hypersensitivity to the larval form of the thimble jellyfish, Linuche unguiculata.[1, 2] Cases have been reported in the Philippines and have been attributed to Linuche aquila and, rarely, Edwardsiella lineata.[3] Most cases occur from March to August, but the incidence peaks in May and June. See the image below.

Seabather’s eruption. Courtesy of DermNet New Zeal Seabather’s eruption. Courtesy of DermNet New Zealand (

See Deadly Sea Envenomations, a Critical Images slideshow, to help make an accurate diagnosis.

See also the Medscape article Cutaneous Manifestations Following Exposures to Marine Life.


Seabather's eruption is a cutaneous hypersensitivity reaction to contact with the larval form (planulae) of the thimble jellyfish, L unguiculata. The eruption typically occurs underneath the bathing garments, which are believed to trap the jellyfish larvae against the skin. Whether the discharge of venom by the trapped larvae plays an important role in the pathogenesis of the eruption remains uncertain. Factors that promote the discharge of venom by the larvae include wearing of bathing suits for prolonged periods following swimming, exposure to fresh water through showering, and mechanical stimulation.


Seabather's eruption is caused by exposure to the larval form (planulae) of the thimble jellyfish, L unguiculata. The seasonal variation in the concentrations of thimble jellyfish larvae in endemic areas lead to the increased incidence of seabather's eruption from May through August, with a peak in May and June.

Freudenthal and Joseph[4] reported the larvae of the sea anemone Edwardsiella lineata as the cause of an outbreak of seabather's eruption on Long Island, New York. This organism also has nematocysts. Various species of Cnidaria larvae in other waters can likely produce similar eruptions.



United States

The incidence of seabather's eruption is seasonal; the highest incidence occurs from May through August. This coincides with the warm gulf streams running along the Atlantic coastline of Florida and the corresponding spawn of thimble jellyfish larvae, which results in the high seasonal concentration of Linuche planulae. In 1997, Kumar et al[5] reported the occurrence of seabather's eruption in Palm Beach saltwater swimmers in May to be 16%.


Seabather's eruption has been reported in Mexico and the Caribbean and along the coast of Brazil.[6, 7, 8] Reports have occurred in the Philippines.[3] The true prevalence of seabather's eruption along other international coastlines remains unknown.


Seabather's eruption occurs independent of race.


Seabather's eruption has been noted with equal frequency in both sexes.


No correlation between age and risk for developing seabather's eruption has been noted. The severity of symptoms, particularly the frequency of fever, is greater in children than in adults.


Cutaneous eruptions clear in 2 weeks, with or without therapy. No deaths have been attributed to exposure to thimble jellyfish larvae.

Patient Education

Educate patients about thimble jellyfish larvae during peak seasons in affected areas and the preventative role of showering with the bathing suit off following exposure to the seawater.

For patient education materials, see Jellyfish Stings and Stingray Injury.




The eruption begins a few hours after bathing in the ocean. Pruritus is the most common symptom in patients with seabather's eruption (98%). It typically lasts 1-2 weeks.

Fever and malaise are the next most commonly observed symptoms (23%). Fever is observed in 18% of patients. However, 40% of patients younger than 16 years report fever compared with 10% of adults. Systemic symptoms, including fever, nausea, abdominal pain, and diarrhea, are more common in children than in adults.

Physical Examination

On physical examination, patients with seabather's eruption typically display inflammatory papules in a distribution pattern that mimics the bathing suit. Lesions have been noted to occur in the axillae; in men with significant chest hair, they occur on the chest.

Relatively rare signs and symptoms of seabather's eruption include the following:

  • Nausea

  • Headache

  • Sore throat

  • Cough

  • Diarrhea

  • Abdominal pain

Two cases have been reported in which seabather's eruption presented as erythematous papules arranged in short linear paths, mimicking jellyfish envenomation from Olindias sambaquiensis and Chrysaora lactea, and resembling in appearance the Koebner phenomenon observed due to scratching of keratosis pilaris, but occurring shortly after sea bathing and not triggered by scratching.[9, 10]


Because of the nature of the allergic hypersensitivity underlying the disease, patients are susceptible to recurrence upon reexposure. Reports have described exaggerated symptomatology in recurrent cases of seabather's eruption, and, for such individuals, avoiding seawater on affected beaches during seasonal peaks is best.





Laboratory Studies

Diagnosis of seabather's eruption is made based on the history of exposure and the physical examination. Laboratory studies and skin biopsy are unnecessary. Although only available for research purposes, Wong et al have demonstrated elevated serum levels of immunoglobulin G antibodies specific for L unguiculata.[11]


A punch biopsy of involved skin may prove useful in narrowing the differential diagnosis when obtaining a reliable history of exposure is difficult.

Histologic Findings

A skin biopsy demonstrates a predominant superficial and deep perivascular and interstitial infiltrate consisting of lymphocytes, eosinophils, and neutrophils. Generally, no epidermal changes are noted, and the dermal-epidermal junction is intact.



Medical Care

Patients with seabather's eruption require only symptomatic or supportive therapy. Children more commonly demonstrate systemic symptoms, including fever, nausea, abdominal pain, and diarrhea.[12] These symptoms may be mistaken for viral gastritis, possibly leading the patient to seek treatment in the emergency department.

Use of topical corticosteroids in combination with antihistamines has yielded variable results. Systemic corticosteroids are generally reserved for patients demonstrating severe symptoms. Many anecdotes regarding the effectiveness of alternative remedies made with vinegar, rubbing alcohol, sodium bicarbonate, sugar, urine, olive oil, and meat tenderizer have been reported.

Patients rarely demonstrate associated systemic symptomatology severe enough to require hospitalization. Even then, treatment is largely supportive and should include systemic corticosteroids.

Surgical Care

No surgical care is necessary to manage seabather's eruption.


A dermatologist can help narrow the differential diagnosis in difficult cases and facilitate a skin biopsy with histologic study.


Diet is unrelated to seabather's eruption.


Limitations on patients with seabather's eruption are unnecessary unless associated systemic symptoms are severe. However, Kumar et al[5] have shown that the risk of developing seabather's eruption in patients exposed to high seasonal concentrations of larvae while swimming in saltwater is significantly reduced if bathers shower with the bathing suit off, regardless of the length of time in the water or the timing of showers.


Showering with the bathing suit off is the only significant protective measure against seabather's eruption. Length of shower time; timing of the shower; bathing suit style; shower water temperature; towel drying upon emerging from the seawater; and application of ointment, creams, or lotions have no preventative effect.



Medication Summary

High-potency topical steroids in combination with oral antihistamines are typically used in treating the cutaneous manifestations of seabather's eruption. Systemic corticosteroids should be reserved for patients with severe rash or pronounced associated systemic symptoms.


Class Summary

These agents have anti-inflammatory properties and cause profound and varied metabolic effects. In addition, these agents modify the body's immune response to diverse stimuli. They are effective in quickly reducing inflammation and pruritus.

Clobetasol (Temovate)

Clobetasol is a class I superpotent topical steroid; it suppresses mitosis and increases the synthesis of proteins that decrease inflammation and cause vasoconstriction. Clobetasol has potent anti-inflammatory properties. Do not use on the groin, axilla, or face.


Class Summary

These agents prevent histamine response in sensory nerve endings and blood vessels. They are more effective in preventing histamine response than in reversing it. They also reduce pruritus.

Loratadine (Claritin)

Loratadine is a second-generation antihistamine with a very low risk of sedation. It selectively inhibits peripheral histamine H1 receptors.

Cetirizine (Zyrtec)

Cetirizine is a second-generation antihistamine with a low risk of sedation. It forms a complex with histamine for H1 receptor sites in the blood vessels, GI tract, and respiratory tract.

Desloratadine (Clarinex)

Desloratadine is a long-acting tricyclic histamine antagonist selective for the H1 receptor. It relieves nasal congestion and the systemic effects of seasonal allergies. It is a major metabolite of loratadine, which, after ingestion, is metabolized extensively to the active metabolite 3-hydroxydesloratadine.

Antihistamine, H1 Blocker

Class Summary

Fexofenadine is a selective antihistamine used to relieve seasonal allergy symptoms (including sneezing, runny nose, itching, and watery eyes) and pruritus. Fexofenadine is available alone and in a combination product

Fexofenadine (Allegra)

Fexofenadine competes with histamine for H1 receptors in the GI tract, blood vessels, and respiratory tract, reducing hypersensitivity reactions. It does not sedate. Fexofenadine is available as a 30-, 60-, or 180-mg tablet. The Allegra ODT tab formulated for disintegration in the mouth immediately following administration. Each orally disintegrating tablet contains 30 mg of fexofenadine hydrochloride. Allegra oral suspension contains 6 mg of fexofenadine hydrochloride per mL or 30 mg/5 mL.


Questions & Answers


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