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Seabather's Eruption

Condition Basics

What is seabather's eruption?

Seabather's eruption is a rash that occurs when a swimmer is stung by marine life larvae. The condition has many names, including sea lice, pika-pika, sea poisoning, sea critters, and ocean itch.

What causes it?

Two types of marine life that generally cause seabather's eruption are:

  • Thimble jellyfish (Linuche unguiculata). These are found seasonally in the water off the Florida coast and across the Caribbean. The jellyfish breed in the Caribbean throughout the summer, peaking in May. The larvae are barely visible, appearing like a speck of finely ground pepper.
  • Sea anemone (Edwardsiella lineata). These are found in the water off the coast of Long Island, New York. The larvae are small ( 2 mm to 3 mm).

Other types of marine life may also cause this rash.

What are the symptoms?

Shortly after being stung, a swimmer may complain of skin discomfort. The rash develops in a few minutes to 12 hours after swimming. The rash consists of raised, hard or soft bumps, or blisters of different shapes and sizes that appear very red and may be extremely itchy. The larvae can become trapped in the fabric of a swimsuit, under swim caps and fins, and along the cuff edges of wet suits and T-shirts. The rash often appears in areas of the body that were covered.

Occasionally, other symptoms may occur with the rash, including nausea, vomiting, headache, fatigue, a general feeling of illness (malaise), pinkeye (conjunctivitis), and urethritis, the inflammation of the tube that carries urine from the bladder to outside of the body (urethra). Fever may occur, particularly in children.

How can you care for yourself?

Home treatment for seabather's eruption can help ease your discomfort and prevent other problems. Try the following treatments.

  • Do not rub your skin.

    If larvae are on your skin, rubbing will cause them to sting.

  • Remove your swimsuit as soon as possible.

    Since larvae can become trapped in the fabric of your suit, it is important to remove a contaminated suit to prevent more stings.

  • Wash your swimsuit.

    If available, rinse your suit in household vinegar or rubbing alcohol.

    Wash your suit in hot, soapy water and dry it in a dryer, if possible, before you wear it again.

  • Shower with fresh water.

    Apply soap and vigorously scrub your skin.

    Do not shower with a contaminated suit on. If larvae are trapped in the fabric of a suit, a freshwater shower will cause the larvae to sting.

  • Take an antihistamine or apply hydrocortisone cream (1%).

    These medicines can help control itching.

    Antihistamine examples include a nondrowsy one like loratadine (Claritin) or one that might make you sleepy like diphenhydramine (Benadryl)

    Do not use the hydrocortisone cream on children younger than age 2 unless your doctor tells you to. Do not use in the rectal or vaginal area in children younger than age 12 unless your doctor tells you to. Also, don't give antihistamines to your child unless you've checked with the doctor first.

  • Use an ice pack.

    This can help relieve pain.

  • Keep the rash clean.

    Wash it every day with soap and water.

  • Watch for symptoms of infection while the rash is present.

    These symptoms include:

    • Increased pain, swelling, redness, or warmth around the affected area.
    • Red streaks extending from the affected area.
    • Drainage of pus from the area.
    • Fever or chills with no other known cause.

The rash will usually go away in 10 to 14 days.


Current as of: March 3, 2021

Author: Healthwise Staff
Medical Review:
William H. Blahd Jr. MD, FACEP - Emergency Medicine
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine
E. Gregory Thompson MD - Internal Medicine
David Messenger MD - Emergency Medicine, Critical Care Medicine