Causes

Swimmer's ear is an infection that's usually caused by bacteria. It's less common for a fungus or virus to cause swimmer's ear.

Your ear's natural defenses

Your outer ear canals have natural defenses that help keep them clean and prevent infection. Protective features include:

• A thin, water-repellent, slightly acidic film lines the ear canal and discourages bacterial growth. Earwax (cerumen) is an accumulation of this waxy film, dead skin cells and other debris that travels to the opening of the ear canal to keep it clean.
• The outer ear, particularly around the opening of the ear canal, helps prevent foreign bodies from entering.

How the infection occurs

If you have swimmer's ear, your natural defenses have been overwhelmed. The conditions that often play a role in infection include:

• Moisture in the ear canal that creates an ideal environment for bacterial growth
• Exposure to contaminated water
• Damage to the sensitive skin of the ear canal that creates an opening for infection