Published on March 8, 2024 at 8:00 / Updated on March 26, 2024 at 8:00

Swimmer's itch is a skin rash caused by parasites sometimes found in bodies of water (lakes, rivers). It is characterized by red plaques that turn into small bumps that look like insect bites. The rash is followed by itching that can last more than 10 days.

Swimmer's itch is not contagious and is not related to water pollution. The condition is usually harmless and resolves within a week or two.


Swimmer's itch is caused by larvae that are released into the water by infected snails. The snails themselves are infected by parasites passed in the feces of infected aquatic birds. Since humans are not suitable hosts for these parasites (called cercariae), they burrow into the skin and soon die. The rash and itching are a reaction to the parasites burrowing into the skin.


Since the rash heals on its own, treatment consists in limiting itching and preventing infection due to scratching. Here are some helpful tips:

  • Use an anti-itch cream or lotion (e.g., calamine)
  • Take an oral antihistamine (e.g., Reactine, Claritin)
  • Apply cold compresses to the affected area
  • Avoid scratching
  • Keep fingernails clean and short

To prevent swimmer's itch, you should:

  • Avoid swimming in bodies of water where outbreaks have been reported
  • Avoid swimming in areas where vegetation is abundant
  • Limit your time in the water
  • Towel off quickly when getting out of the water
  • Shower after getting out of the water
  • Warn other swimmers if you or your child develop a skin irritation within a few hours of swimming

When should I see a health professional?

  • If a rash develops after swimming and lasts for more than 3 days.
  • If fluid is weeping from the affected area.
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