Causes of otitis externa

Otitis externa refers to an inflammation of the skin of the external ear canal. Bacterial in origin in 90% of cases, this pathology can be aggravated by environmental, anatomical or disease-related factors. Certain behaviours can also traumatise the ear canal tissue. The use of cotton buds in the external auditory canal, the use of certain irritatant products, humid environments or frequent bathing can lead to this type of otitis.

Otitis externa is the most common cause of ent consultations. This pathology, which has an infectuous origin, can be  caused by various factors. What are they?

What is otitis externa?

There are several types of otitis : acute otitis media, serous otitis, otitis externa... These pathologies differ from one another by their location, symptoms and causes.

Otitis externa (OE) is an ear disease this is the most frequent reason for ENT consultations.(1) Characterised by an acute inflammation of the outer ear, OE is located more precisely in the tissues of the external auditory canal (EAC). In 90% of cases, otitis externa is diffuse: the entire skin of the ear canal is then affected by the inflammation. (2)

The symptoms of otitis externa are the following: sensation of fullness in the ear, itching, intense pain in the external auditory canal, among others. Clear and then purulent flow may also add to these symptoms, as well as EAC obstruction.(3)

Itching, pain and swelling: why does my ear hurt?

What causes otitis externa?

In about 90% of cases, otitis externa is bacterial, i.e. it is caused by the proliferation of certain germs, such as Staphylococcus aureus or Pseudomonas aeruginosa. The rest of the time, OE is often mycotic. Generally, the fungi involved are of the Aspergillus and Candida species.(1)(4)

Favourable actions and environments

Behavioural and environmental factors can traumatise the skin of the external ear canal, alter its balance and cause otitis externa. Indeed, frequent scratching, rough cleaning and the use of cotton buds in the EAC greatly increases the risk of inflammation of the skin of the ear canal. (5)(6)

Warm, humid environments also facilitate episodes of otitis externa, as does swimming in lakes and pools. These causes are so notable that they have given the OE an alternative name: swimmer's ear . Specifically, perspiration and water stagnation within the EAC can create tiny lesions in the canal skin, modify the local bacterial flora and promote the proliferation of infectious organisms.(1)(4)

The use of products that irritate the EAC (soaps, shampoos, foam baths, etc.) and the wearing of an ill-fitting hearing aid can also cause injuries in the ear canal and result in OE.(5)

Finally, the presence of a wax impaction within the external ear canal can cause otitis externa. Especially if it's thick!(1)(5)

I would like to know more about the symptoms of an ear blockage.

Anatomical factors

Various anatomical features can affect the ability of the external ear canal to self-clean. If the EAC is long, narrow, angled, or has significant hair growth, the natural drainage of the earwax and humidity can be difficult.(7)

The diseases and drugs involved

People with diabetes and those with a skin disease such as psoriasis or eczema are more likely to develop otitis externa. In some individuals, the use of immunosuppressants or antibiotics may also promote the occurrence of OE. (5)(8)

How can i prevent otitis externa?

Now that we have reviewed the possible causes of otitis externa, here are some preventive measures to take:

  • Dry your ears well after swimming,
  • Adopt a regular ear cleansing routine
  • Avoid the use of cotton buds inside the EAC

I'm still learning: how do I relieve ear pain?


(1) Otites externes : une maladie auto-infligée ? F. Bizindavyi J.-P. Guyot M.-I. Kos Rev Med Suisse 2007; volume 3. 32569.
(2) Batthikhi MN, Ammar SI. Otitis externa infections in Jordan, Saudi Med J 2004;25:1199-203. https://openmicrobiologyjourna...
(3) Symptômes, diagnostic et évolution d’une otite externe. 2019.
(4) Société canadienne de pédiatrie, comité des maladies infectieuses et d’immunisation. L’otite externe aiguë. Paediatr Child Health. 2013;18(2):99-101.
(5) Otite externe : définitions et causes. 2019.
(6) 2 Ong YK, Chee G. Infections of the external ear. Ann Acad Med Singapore,
(7) Roeser RJ, Ballachanda BB. Physiology, pathophysiology and anthropology/epidemiology of human ear canal secretions. J Am Acad Audiol 1997;8:391-400.
(8) Russell JD, Donnelly M, McShane DP, Alun-Jones T, Walsh M. What causes otitis externa ? J Laryngol Otol 1993;107:898-901.