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  • Writer's pictureDr. Koralla Raja Meghanadh

What are the causes of an ear infection?

Updated: Mar 16

The most common type of ear infection is a middle ear infection followed by external ear infections like Otitis externa and Otomycosis.

What causes an ear infection? Middle ear infection

What causes a middle ear infection?

The most common ear infection cause is the middle ear infection. 90% of the middle ear infections spread from the nose to the ear through the eustachian tube. What causes middle ear infection is a common cold or bacterial infection or chronic sinusitis. The secretions or phlegm from the nose travels to the back of the nose, called the nasopharynx. The middle ears open into the nasopharynx through the eustachian tube, i.e., designed to move air into the middle ear. When a person blows out his nose, it increases pressure in the nasopharynx. This pressure can push the phlegm from the nasopharynx into the middle ear through the eustachian tube.

Whether it is due to common cold or chronic sinusitis treating the primary cause or source of infection is necessary for middle ear infection. Unlike in rhinitis or the common cold, where the patient experiences inconvenience due to a runny nose, chronic sinusitis doesn't give out many symptoms and doesn't trouble the patient. Hence, the likelihood of a person treating primary infection is less in sinusitis compared to the common cold which could, in turn, make the middle ear infection worst. You can read our article "Ear pain or clogged ears with a sinus infection."

What causes an external ear infection like Otitis externa and Otomycosis?

What causes an external ear infection is infected water or external infected objects like bud, key, or pin inserted into the ear. There will always be wax formation in the ear, and it keeps coming out. While the wax is coming out at the exit point, we can experience an irritation that pushes people to remove the wax and satisfy the urge. The object used to remove the wax can contain bacteria or fungus. If this object causes trauma to the ear's skin, the bacteria and fungus can quickly enter the skin through the damage.

What causes an ear infection? What causes external ear infections like Otitis externa and Otomycosis?

Otitis externa

Otitis externa is a bacterial infection caused in the external ear. In this bacterial infection, we can experience pain and a watery discharge. Otitis externa is the second most common type of ear infection in non-humid areas irrespective of the season.


Otomycosis is a fungal infection in the external ear that starts with itching, and in later stages, this itching can worsen, and pain might begin in the ear. This outer ear infection is more common in humid or coastal areas.

Please read this article to understand more about Otomycosis.

An article by

Dr. K. R. Meghanadh


Where does an ear infection start?

Ear infections can start from different parts of the ear. In most cases, ear infections start in the middle ear. Middle ear infections are secondary infections triggered by a common cold or chronic sinusitis. As the infection progresses, it can spread to other ear parts.

The external ear is the second most common place for an ear infection to start. This outer ear infection can either be bacterial or fungal.

On the other hand, the inner ear is the least common location for an infection to start. It usually occurs as a secondary infection, like a middle ear infection. However, the infection in the inner ear can spread from the brain to the inner ear in very rare cases. In most inner ear infection cases, the spread is from the middle ear to the inner ear.

It's essential to identify the symptoms of an ear infection and seek timely medical assistance to prevent complications.

What is the most common ear infection?

The most common ear infection is the one that affects the middle ear, i.e., otitis media. This is a secondary infection that mostly occurs due to an untreated common cold.

Otitis media is then succeeded by infections of the external ear. Otitis externa, a bacterial infection, is the second most common ear infection in non-humid or non-coastal regions. Otomycosis, a fungal infection, is the second most common ear infection in humid or coastal areas.

What happens if you ignore an ear infection?

If you ignore an ear infection, it can propagate to different parts of the ear and cause severe complications such as perforation of the eardrum, damage to the middle ear bones (stapes, incus, malleus), and permanent hearing impairment. The spread of the infection to the inner ear can also result in tinnitus and vertigo and, in severe cases, even lead to brain infection.

As a result, affected individuals may require hearing aids, surgery, or a combination of both. Therefore, it is essential to seek prompt medical attention if one suspects an ear infection.

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