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Otitis externa

What is normal?

The outer ear canal is a tunnel that runs from the ear hole to the eardrum. It is about 3 cm long and is lined with normal skin containing hairs and glands that produce wax (see diagram). The outer ear canal is a blind (closed) tunnel and normally drains only through the ear hole.

What is otitis externa?

Otitis externa is a condition in which the skin lining the outer ear canal becomes red and swollen due to infection. This infection occurs commonly because of water entering the ear canal and is sometimes referred to as 'swimmer's ear'. In the tropics, the heat and high humidity cause people to perspire excessively in summer, and this moisture may also play a part in causing otitis externa or 'tropical ear'.

What are the symptoms?

Pain and tenderness of the ear canal are typical, and in severe cases the pain and tenderness may spread to the outer ear and surrounding skin. Other symptoms include discharge from the outer ear canal, itching and reduced hearing.

Why does it occur?

Water entering the outer ear canal can drain only through the ear hole. The outer ear canal is horizontal and curved; it may contain wax. Water may not drain freely and can cause skin to become soggy, so allowing bacteria or fungi, normally present on the skin, to cause infection.

Who is more prone to otitis externa?

You are more likely to suffer from otitis externa if your outer ear canal is narrow or long, or if the skin lining the canal is in poor condition (i.e. if it is not waterproofed by the wax and is wet by regular swimming). Incidentally, chlorinated fresh water is more damaging than salt water.

The skin lining will deteriorate too if it is prone to dermatitis or eczema and if exposed to chemicals (e.g. hair shampoo, hair dyes and ear ointments). The ear canal can be damaged by attempting to clean it with a hairpin.

What is the treatment?

The basis of successful treatment is to clean the canal and keep it empty and dry. In mild cases your doctor will treat the infection by cleaning the outer ear canal using suction or a probe and then prescribing cream to insert several times a day. The ear cream is used for about 5 days and contains chemicals that kill the bacteria or fungus causing the infection.

If the infection is severe and the outer ear canal is swollen, the doctor may insert a cotton wick coated with the healing cream into the ear canal.

How can otitis externa be prevented?

You can take a number of steps to prevent otitis externa. Among them are:

• Avoid getting water in your ear.
• If water enters, shake it out or use Aquaear drops.
• Use moulded earplugs or a bathing cap when swimming.
• Use earplugs or a cap when showering.
• Use earplugs when washing your hair.
• Coat cottonwool with petroleum jelly (Vaseline) before insertion in ears.
• Avoid poking objects such as hairpins and cotton buds in the ear to clean the canal.
• The ear usually cleans itself naturally. Do not attempt to clean it and risk infection of the canal or damage to the eardrum. If you have a problem, contact your doctor for advice and treatment.

Copyright 1995: John Murtagh, Professor of General Practice
Monash University, Melbourne, Australia