Causes of otitis externa

There are several different causes of otitis externa. A number of things can also increase your chance of developing the condition.

Common causes

Causes of otitis externa can include:

• a bacterial infection usually bybacteria called Pseudomonas aeruginosa or Staphylococcal infections aureus
• seborrhoeic dermatitis a common skin condition where the naturally greasy areas of your skin become irritated and inflamed, which can sometimes affect the ears
• a middle ear infection (otitis media) discharge produced by an infectiondeeper in the ear can sometimes lead to otitis externa
• a fungal infection such asfrom the Aspergillus variety and the Candida albicans variety (which also causes thrush); fungal infections are more common if youuse antibacterial or steroid ear drops for a long time
• irritation or an allergic reaction otitisexterna can occur because of a reaction to something that comes into contact with your ears, such as ear medication, ear plugs, shampoo or sweat

Otitis externa can also return after previous treatment if you don't complete the full course.

Possible triggers

The following thingsaren't direct causes of otitis externa, but may make the condition more likely to develop.

Excessive moisture

Liquid in your ear canal can make you more likely to develop an infection.Moisture provides an ideal environment for bacteria and to a lesser degree, fungito grow.

Your risk may be increased by:

• swimmingparticularly in dirty or polluted water
• sweating
• being exposed to humid environments

Water can also wash away earwax inside your ears, which canmake them itchy.

Ear damage

Your ear canal is very sensitive andmay become damaged through:

• scratching inside your ears
• excessive cleaning
• inserting cotton buds
• wearing ear plugs or in-ear headphones for long periods

Usinga hearing aid may also increase your risk of developing otitis externa.

Chemicals

Your chances of getting otitis externa are increased if you use certain products in or near your ears, such as:

• hair sprays
• hair dyes
• earwax softeners

Underlying skin conditions

As well as seborrhoeic dermatitis,certain underlying skin conditions canincrease your risk ofotitis externa. These include:

• psoriasis
• eczema
• acne

Allergic conditions

If you have allergic rhinitis or asthma , you may be at a higher risk of developing otitis externa.

Weak immune system

You may be at higher risk of developing otitis externa if you have a condition that can weaken your immune system, such as:

• diabetes
• HIV or AIDS

Certain cancer treatments, such as chemotherapy , may also increase your risk of otitis externa.

Inflammation

Inflammation is the body's response to infection, irritation or injury, which causes redness, swelling, pain and sometimes a feeling of heat in the affected area.