If you go swimming before the membrane heals, the result can be an infection that is mild at first but can progress to severe pain, fever and other complications.

The Centers for Disease Control and Prevention estimate that 36 percent of children ages 7 to 17 years old and 15 percent of adults swim at least six times during the year, creating a large number of potential ear infection opportunities. The term for illnesses that result from swimming is recreational water illnesses (RWI), which are the product of bacteria or germs that are ingested or otherwise enter the body by contacting contaminants found in water.

The Ear's Natural Defenses

Swimmer’s ear is usually prevented because the outer ear canals have protections in place to prevent infection. These include glands that produce a wax-like substance to form a water-repellent barrier on the skin inside the ear and discourages bacteria growth and the downslope of the ear canal, which helps to drain any water that gets into the space.

However, these defenses can be overwhelmed under certain circumstances, allowing bacteria to grow, and swimming isn’t the only cause. Excessive moisture in the ear caused by humid weather or heavy perspiration from hot weather can also accumulate in the ear canal. Then, when cleaning the ear or poking at an itch with a finger, the skin breaks, allowing the bacteria present to invade. There are also certain jewelry or hair products that can cause an allergic reaction or skin condition that helps to promote infection.

If someone swims a lot, particularly if it’s in a body of water like a lake that has elevated bacteria, they may be more susceptible to acquiring swimmer’s ear, simply because they are immersing themselves in water that contains more bacteria than the chlorinated water of a pool. Anyone with a narrow ear canal, like children, can more easily trap water inside the ear, and headphone buds or hearing aids inserted into the ear also have a chance of breaking the skin.