Swimmer's itch

What is swimmer’s itch?

Swimmer's itch (cercarial dermatitis) is an irritating rash that can develop after swimming or wading outdoors. While most common in freshwater lakes and ponds, it can also occur in saltwater. This condition results from the body's allergic reaction to the larvae of certain microscopic parasites, which latch on and burrow into the skin when swimming in areas where these parasites live.

Although uncomfortable, swimmer's itch usually clears up on its own within a few days to a week. It's crucial not to scratch, as this can break the skin and lead to infection. Over-the-counter remedies or prescription medication can help control the itch. Your MinuteClinic® provider can assess symptoms and recommend a treatment plan to alleviate irritation. Importantly, swimmer's itch is not contagious.

Symptoms of swimmers itch

Symptoms include burning, tingling, and itching of the infected skin. The rash, appearing as small reddish pimples within 12 hours of exposure, may develop into small blisters. Typically affecting exposed skin not covered by swimsuits, waders, or wetsuits, symptoms tend to worsen with each subsequent exposure to the parasite.

What causes swimmer’s itch?

The parasites responsible for swimmer's itch live in the blood of waterfowl and mammals near lakes and ponds, including ducks, geese, gulls, beavers, and muskrats. The eggs enter the water through host animal feces. After hatching, the parasites evolve into cercariae, the next stage of their lifecycle, inside certain snail species near the shoreline. Although humans are not suitable hosts, the larvae can cause an allergic reaction by burrowing into the skin before dying.

How is swimmer’s itch treated

Swimmer's itch typically resolves on its own, and over-the-counter products can help relieve itching. In severe cases, prescription medication may be necessary.

How do I reduce the risk of swimmer’s itch

Apply waterproof sunscreen before entering the water to protect against the parasite.

  • Avoid shallows near the shoreline, opting for deeper water if you're a strong swimmer and steering clear of marsh areas where snails reside.

  • Choose swimming spots carefully, avoiding known swimmer's itch problem areas and checking for warning signs.

  • Refrain from feeding birds near swimming areas or docks.

  • Rinse skin immediately after swimming, thoroughly drying with a towel, and launder swimsuits after each use. Reapply sunscreen if staying in the sun.