Otitis externa refers to an infection of the ear canal (outer ear), the
tube leading from the outside opening of the ear in towards the ear drum.
The infection usually develops in children and adolescents whose ears are
exposed to persistent, excessive moisture.
The external ear canal is a tube approximately 1 in (2.5 cm) in length
that runs from the outside opening of the ear to the start of the middle
ear, which is behind the tympanic membrane (ear drum). The canal is partly
cartilage and partly bone. The lining of the ear canal is skin, which is
attached directly to the covering of the bone. Glands within the skin of
the canal produce a waxy substance called cerumen (popularly called
earwax). Cerumen is designed to protect the ear canal, repel water, and
keep the ear canal too acidic to allow bacteria to grow.
Continually exposing the ear canal to moisture may cause significant loss
of cerumen. The delicate skin of the ear canal, unprotected by cerumen,
retains moisture and becomes irritated. Without cerumen, the ear canal
stops being appropriately acidic, which allows for the growth of
microorganisms. Thus, the warm, moist, dark environment of the ear canal
becomes a hospitable environment for development of an infection.
Otitis externa is commonly referred to as swimmer's ear.
Although all age groups are affected by otitis externa, children,
adolescents, and young adults whose ears are exposed to persistent,
excessive moisture develop the infection most often. Otitis externa occurs
most often in warm climates and during the summer months, when more people
are participating in water activities. The ratio of occurrence in males is
equal to that of females. People in some racial groups have a smaller size
of the ear canal, which may predispose them to infection.
Causes and symptoms
Chidren and adolescents with otitis externa often have been diving or
swimming for long periods of time, especially in polluted lakes, rivers,
or ponds. Routine showering can also lead to otitis externa. Water in the
ear canal can carry infectious microorganisms into the ear canal.
Bacteria, fungi, and viruses have all been implicated in causing otitis
externa. However, most commonly otitis externa is caused by bacteria,
. Other bacteria that can cause otitis externa
, and bacteria of the family called Streptococci. Occasionally, fungi may
cause otitis externa. These include
. Two types of viruses, called herpesvirus hominis and varicella-zoster
virus, have also been identified as causing otitis externa.
Other conditions predisposing to otitis externa include the use of cotton
swabs to clean the ear canals. This pushes cerumen and normal skin debris
back into the ear canal, instead of allowing the ear canal's normal
cleaning mechanism of the ear to work, which would ordinarily move
accumulations of cerumen and debris out of the ear. Also, putting other
items into the ear can scratch the canal, making it more susceptible to
infection. For example, children may insert a foreign body in their ear
canal and not mention it to their parents. Hair spray or hair coloring,
which can irritate the ear canal, may also lead to otitis externa. A
hearing aid can trap moisture in the ear canal and should be taken out as
often as possible to allow the ear an opportunity to dry out.
The first symptom of otitis externa is often
of the ear canal, followed by watery discharge from the ear. Eventually,
the ear begins to feel extremely painful. Any touch, movement, or pressure
on the outside structure of the ear may cause severe
. If the canal is excessively swollen, hearing may become muffled. The
canal may appear swollen and red, and there may be evidence of
foul-smelling, greenish-yellow pus.
In severe cases, otitis externa may be accompanied by
. Often, this indicates that the outside ear structure has become infected
as well. It will become red and swollen, and there may be enlarged and
tender lymph nodes in front of, or behind, the ear.
A serious and life-threatening type of otitis externa is called malignant
otitis externa. This is an infection that most commonly affects persons
who have diabetes or in persons with weakened immune systems. In malignant
otitis externa, a patient has usually had minor symptoms of otitis externa
for some months, with pain and drainage. The causative bacteria is usually
. This bacteria spreads from the external canal into all of the nearby
tissues, including the bones of the skull. Swelling and destruction of
these tissues may lead to damage of certain nerves, resulting in spasms of
the jaw muscles or paralysis of the facial muscles. Other, more severe,
complications of this destructive infection include
(swelling and infection of the coverings of the spinal cord and brain),
brain infection, or brain abscess (the development of a pocket of
infection with pus).
The doctor should be called if any of the following symptoms are present:
Diagnosis of uncomplicated otitis externa is usually quite simple. The
symptoms alone, of ear pain worsened by any touch to the outer ear, are
characteristic of otitis externa. Examination of the ear canal will
usually reveal redness and swelling. It may be impossible (due to pain and
swelling) to see much of the ear canal, but this inability itself is
If there is a need to identify the types of organisms causing otitis
externa, the canal can be gently swabbed to obtain a specimen. The
organisms present in the specimen can then be cultured (allowed to
multiply) in a laboratory, and then viewed under a microscope to allow
identification of the causative organisms.
If the rare infection malignant otitis externa is suspected,
scan (CT scan) or
magnetic resonance imaging
(MRI) scans will be performed to determine how widely the infection has
spread within bone and tissue. A swab of the external canal will not
necessarily reveal the actual causative organism, so some other tissue
sample (biopsy) will need to be obtained. The CT or MRI will help the
doctor decide where the most severe focus of infection is located, in
order to guide the choice of a biopsy site.
Otitis externa us usually not a dangerous condition and often clears up by
itself within a few days. To aid in the healing, the infected ear canal
can be washed with an over-the-counter topical antiseptic. Pain can be
relieved be placing a warm heating pad or compress on the infected ear as
well as through the use of an over-thecounter pain reliever such as
or aspirin. During the healing process, the infected ear canal must be
kept dry, even while showering, through the use of ear plugs or a shower
If the pain worsens or does not improve within 24 hours, or for the
fastest way to relieve pain and to prevent
the spread of infection, the doctor should be seen. The doctor will clean
the ear with a suction-tipped probe or other type of suction device to
relieve irritation and pain.
will applied directly to the skin of the ear canal (
) to fight the infection. These antibiotics are often combined in a
preparation that includes a steroid medication that reduces the itching,
inflammation and swelling within the ear canal. For full treatment,
eardrops are usually applied several times a day for seven to 10 days.
If the opening to the ear is narrowed by swelling, a cotton wick may be
inserted into the ear canal to help carry the eardrops into the ear more
effectively. The medications are applied directly to the wick, enough
times per day to allow the wick to remain continuously saturated. After
the wick is removed, usually after about 48 hours, the medications are
then put directly into the ear canal three to four times each day.
For severe infection, oral antiobiotics may be prescribed. If the otitis
externa infection is caused by the presence of a foreign body in the ear,
the infection will not improve until the foreign body is removed.
In malignant otitis externa, antibiotics will almost always need to be
given intravenously (IV). If the CT or MRI scan reveals that the infection
has spread extensively, these IV antibiotics will need to be continued for
six to eight weeks. If the infection is in an earlier stage, two weeks of
IV antibiotics can be followed by six weeks of antibiotics by mouth.
) oil has anti-inflammatory properties and may be apppied to the infected
ear canal (one to three drops every three hours) to help soothe and heal
the ear. Garlic (
) is a natural antibiotic. Garlic juice can be combined with equal parts
of glycerin and a carrier oil such as olive or sweet olive and applied
(one to three drops) to the infected ear every three hours.
The prognosis is excellent for otitis externa, for it is usually easily
treated. Basic treatment measures will cure 90 percent of cases without
complication. However, it may recur in certain susceptible individuals.
Left untreated, malignant otitis externa may spread sufficiently to cause
—The medical term for earwax.
—A paper-thin covering stretching across the ear canal that
separates the middle and outer ears.
—A disease caused by a virus or a bacterium. Examples of viruses
causing an infectious disease are: HIV-1 virus, herpes simplex,
cytomegalovirus, Epstein-Barr virus, leukemia virus. Examples of
bacterial infectious diseases are: syphilis and tuberculosis.
—Outer visible portion of the ear that collects and directs sound
waves toward the tympanic membrane by way of a canal which extends
inward through the temporal bone.
Parents should teach their children how to clean their ears without using
sharp objects and to dry their ears thoroughly after swimming, showering,
"External Otitis." In
Nelson Textbook of Pediatrics
, ed. Richard E. Behrman. Philadelphia: W. B. Saunders Co., 1996.
Friedman, Ellen M.
My Ear Hurts!
"Keep Your Ears Dry."
Consumer Reports on Health
, 7, no. 7 (July 1995): 80+.
Moss, Richard. "Swimmers Ear."
Pediatrics for Parents
17, no. 4 (Apr. 1996): 3+.
American Academy of Otolaryngology-Head and Neck Surgery, Inc. One Prince
St., Alexandria VA 22314-3357. (703) 836-4444. Web
"Healthy Swimming." National Center for Infectious Diseases,
Centers for Disease Control and Prevention.