It can result from an injury, such as might occur if you use a Q-tip to clean your ears. It can also be caused by dirty water in your ears. Frequent showering or swimming can increase the risk of getting an infection. Otitis externa often occurs in the summer from swimming in polluted water. Hair spray or hair dye may irritate the ear canal as well.
Some people get otitis externa repeatedly, especially if they clean their ears too vigorously.
People who have allergies also seem particularly prone to otitis externa. In some cases, swelling or pus may affect your hearing. Your health care provider will examine your ears with a viewing instrument. He or she may take a sample of pus and culture it to look for bacteria or fungi. Your provider will carefully clean and dry your ear.