Swimmer’s Itch: Causes, Symptoms, And Treatment

Swimmer’s itch or cercarial dermatitis is a skin rash that develops after you swim outdoors. This itchy rash develops as an allergic reaction to certain parasites called “cercaria.” Infected snails release these parasites into salt and fresh water.

When you swim, these parasites penetrate into your skin, causing the rash. As humans are not suitable hosts, the parasite cannot develop inside the human body and die soon after entering the skin.


Causes Of Swimmer’s Itch

Causes Of Swimmer's Itch: Parasite called cercaria

The parasites that cause swimmer’s itch live in the blood of ducks, geese, swans, muskrats, and beavers. Through the feces of these hosts, the parasite’s eggs can enter the water, where they infect a certain species of aquatic snail and multiply.1


The larvae released by these infected snails in the water is what penetrates the human skin where it cannot live but cause an allergic reaction. The risk of swimmer’s itch increases in summer as the water reaches the ideal temperature for the snails to reproduce and grow. Swimmer’s itch can also develop in a swimming pool if the water contains the infected snails. This usually occurs when the water in the pool is not clean or chlorinated.

Symptoms Of Swimmer’s Itch

Symptoms Of Swimmer's Itch: rashes, pimples, and blisters


The severity of symptoms increases with repeated exposure to contaminated water. The more you swim in the contaminated water, the greater the risk of developing serious and immediate symptoms.

Initially, you may experience burning, itching, or a tingling sensation in the exposed area. After about 12 hours, you might notice small reddish pimples that later develop into blisters. Fortunately, the rash occurs only in the areas that are exposed to the water. So, the skin under the swimwear remains unaffected.2


The parasites do not spread from one person to another and the rashes developed due to swimmer’s itch are not contagious. This is because the parasite dies once it penetrates the human body.

Treatment For Swimmer’s Itch

Treating swimmer's itch: cold compress


Swimmer’s itch is difficult to diagnose as there are no blood tests that can specifically tell you that the itching is caused by the cercaria parasite. It is also confused with other diseases such as chickenpox, poison ivy, or even herpes, as it shows similar symptoms.3

This condition doesn’t require medical attention as the symptoms usually resolve in 1 – 2 weeks. However, anti-itch creams and antihistamines are used to reduce the itching. If the itching is severe, your doctor may recommend prescription medicines to reduce the symptoms. Avoid scratching the rash as it can increase the risk of infections.


Unless you have severe itching, you can use these home remedies to relieve the itch.

  • Apply a cold compress.
  • Apply a paste of water and baking soda to the affected area.
  • Bathe in baking soda or Epsom salts.
  • Wash the rash with diluted vinegar.

Avoid wearing clothes that can irritate the skin further. Wear cotton clothes instead of synthetic fabrics.


Note: Larvae tend to be present in the shallow water. So, avoid the shoreline to prevent swimmer’s itch. Always shower once you swim in a pond or lake and dry yourself.