Swimmer's itch is an itchy rash that can occur after you go swimming or wading outdoors. Also known as cercarial dermatitis, swimmer's itch is most common in freshwater lakes and ponds, but it occasionally occurs in salt water.
Swimmer's itch is a rash usually caused by an allergic reaction to parasites that burrow into your skin while you're swimming or wading in warm water.
The parasites that cause swimmer's itch normally live in waterfowl and some animals. These parasites can be released into the water. Humans aren't suitable hosts, so the parasites soon die while still in your skin.
Swimmer's itch is uncomfortable, but it usually clears up on its own in a few days. In the meantime, you can control itching with over-the-counter or prescription medications.