External otitis is an infection of the skin of the ear canal.
External otitis may involve the entire canal, as in generalized or acute external otitis, or just one small area, as when pus accumulates in a boil (furuncle) or pimple. Malignant external otitis (see Outer Ear Disorders: Malignant External Otitis) is a very severe external ear infection that involves the bone of the skull (osteomyelitis—see Bone and Joint Infections: Osteomyelitis) and can spread to other parts of the skull (the temporal bone).
A variety of bacteria, such as Pseudomonas aeruginosa or Staphylococcus aureus or, rarely, fungi can cause generalized external otitis. Boils are usually caused by Staphylococcus aureus. Certain people, including those who have allergies, psoriasis, eczema, or scalp dermatitis, are particularly prone to external otitis. Injuring the ear canal while cleaning it or getting water or irritants, such as hair spray or hair dye, in the canal often leads to external otitis. External otitis is particularly common after swimming, in which case it is sometimes called swimmer's ear. Earplugs and hearing aids make external otitis more likely, particularly if these devices are not properly cleaned. Use of cotton-tipped applicators are a very common risk factor for external otitis.
Symptoms of generalized external otitis are itching and pain. Sometimes an unpleasant-smelling white or yellow discharge drains from the ear. The ear canal may have no swelling or slight swelling, or, in severe cases, it may be swollen completely closed. If the ear canal swells or fills with pus and debris, hearing is impaired. Usually, the canal is tender and hurts if the external ear (pinna or auricle) is pulled or if pressure is placed on the fold of skin in front of the ear canal (tragus).
Fungal external otitis causes more intense itching than pain, and people have a feeling of fullness in the ear.
Boils cause severe pain. When they rupture, a small amount of blood and pus may leak from the ear.
The doctor bases the diagnosis on an examination of the ear canal. To a doctor looking into the ear canal through an otoscope (a device for viewing the canal and eardrum), the skin of the canal appears red and swollen and may be littered with pus and debris. An infection caused by a fungus is also diagnosed based on examination or culture (a sample of the pus and debris is grown in a laboratory to identify the microorganisms). Often, fungal spores can be seen in the ear canal.
Swimmer's ear may be prevented by putting drops of a solution containing half rubbing alcohol and half vinegar in the ear immediately after swimming (as long as there is no hole, perforation, in the eardrum.
Attempting to clean the canal with cotton swabs interrupts the normal, self-cleaning mechanism and can push debris toward the eardrum, where it accumulates. Also, these actions may cause minor damage to the delicate skin of the canal that predisposes to external otitis.
To treat generalized external otitis due to any cause, a doctor first removes the infected debris from the canal with suction or dry cotton wipes. After the ear canal is cleared, hearing often returns to normal. Usually, a person with mild external otitis is given ear drops containing vinegar and drops containing a corticosteroid such as hydrocortisone to use several times a day for up to a week. Vinegar is helpful because bacteria do not grow as well once the normal acidity of the ear canal is restored. With moderate or severe infection, antibiotic ear drops also are prescribed. If the ear canal is very swollen, a doctor inserts a small wick into the ear canal to allow the drops to penetrate. The wick is left in place for 24 to 72 hours, after which time the swelling may have gone down enough to allow people to put the drops directly into the ear canal.
People who have severe external otitis may need to take antibiotics by mouth, such as cephalexin or ciprofloxacin.
Analgesics such as acetaminophen or codeine may help reduce pain for the first 24 to 48 hours, until the inflammation begins to subside.
To treat fungal external otitis, doctors thoroughly clean the ear canal and insert antifungal ear drops. Repeated cleanings and treatments may be needed. A combination of rubbing alcohol and white vinegar is particularly effective in fungal external otitis.
Treatment of boils depends on how advanced the infection is. In an early stage of infection, a heating pad can be applied for a short time and analgesics, such as oxycodone with acetaminophen, can be given to help relieve pain. The heat may also help speed healing. A boil that has come to a head is cut open to drain the pus. An antibiotic is then given by mouth.
Last full review/revision February 2013 by Bradley W. Kesser, MD