What is Swimmer’s Itch? Symptoms and How to Treat It

Swimmer’s itch is a skin rash caused by an allergic reaction to the larvae of microscopic parasites found in both fresh and salt water. These parasites typically live in snails, which release larvae into the water, according to the CDC.

Swimming in polluted water, even for a short period of time, can cause swimmer’s itch, and after you come into contact with the larvae, “when the skin dries, those parasites burrow under people’s skin and cause an itchy rash,” says Dr. Christina Boull, MD, an associate professor of dermatology and pediatrics at M Health Fairview University of Minnesota Medical Center. Read on to learn what symptoms to look out for and what precautions you can take to avoid this unpleasant summer rash.

What is swimmer’s itch?

You can recognize swimmer’s itch, also called cercarial dermatitis, by the tiny red dots that appear on your skin after you’ve been exposed to the parasites, Boull says. The rash will likely appear on skin that’s directly exposed to the water, as opposed to skin that’s protected by your swimsuit. For this reason, your arms and legs are particularly vulnerable to swimmer’s itch, she says.

These spots typically appear 12 hours after exposure, and over the next day or two, some people can experience a more severe reaction with welts and blisters. “One of the major risk factors for complications from this rash would be a secondary bacterial infection.” If you scratch the rash, there’s a chance that staph bacteria can get under your skin, making your body vulnerable to developing staph infections like impetigo or cellulitis, she says.

What could be mistaken for swimmer’s itch?

When it comes to swimming in the ocean, a swimmer’s eruption is a skin rash that shares similar symptoms to swimmer’s itch. As for identifying whether your rash is swimmer’s itch or swimmer’s eruption, the latter typically develops under a swimsuit, Boull explains. In comparison, swimmer’s itch is more common in areas that aren’t protected by a swimsuit, she reiterates.

In addition, swimmer’s itch is often mistaken for bites from small insects, such as mosquitoes, because they are small red bumps, Boull says.

How do you get rid of swimmer’s itch?

“The good news is that it goes away on its own,” Boull says. Because humans are the mites’ favorite hosts, they don’t live very long in the skin. Typically, the rash and itching improve significantly over the course of a week, although it’s possible for it to last as long as three weeks, she says.

To control the itching of the rash, Boull recommends 1% hydrocortisone, an over-the-counter topical steroid cream. She also recommends taking an oral antihistamine.

For severe itching, prescription oral prednisone and oral cortisone medications can relieve the itching and inflammation.

If your swimmer’s itch has progressed to blistering, open sores, and you’re experiencing a fever, it could be a sign of secondary bacterial infection. In this case, it’s essential to see a doctor who can prescribe oral antibiotics, says Boull.

Does showering help with swimmer’s itch?

The parasites that cause swimmer’s itch can only get into your skin after you dry off. “So it’s really important that after you get out of a lake or an area where you’re swimming that might have snails, you grab a towel and wipe the water off your skin.” Showering after you get out of the water can also help prevent the parasites from getting under your skin.

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Snails tend to prefer warm, shallow water, so avoiding these areas can help limit your chances of exposure to the parasites. Finally, be aware of “No Swimming” signs, which can indicate if there are pathogens in the water.