What is the most common cause of swimmer's ear?

The most common cause of swimmer's ear, also known as otitis externa, is bacteria. This condition typically arises when water gets trapped in the ear canal, creating a moist environment that promotes bacterial growth. Common bacterial organisms responsible for swimmer’s ear include Pseudomonas aeruginosa and Staphylococcus aureus, both of which thrive in warm, wet conditions.

While viruses, fungi, and parasites can lead to ear issues, they are less frequently associated with swimmer's ear compared to bacteria. Viruses may lead to other ear infections, fungi can cause different types of external ear conditions, and parasites usually do not affect the outer ear in the same way that bacteria do. Understanding that bacteria are the primary pathogens in this context helps in preventive measures, such as ensuring ears are dried properly after swimming and using ear drops designed to help prevent moisture accumulation.