How Does an Ear Infection Happen?

Dr. K. R. Meghanadh

Ear infections are among the most common infections affecting people of all ages, from infants to adults. They often catch us off guard with sudden blockage, pain or discomfort. But how exactly does an ear infection happen? This article will explore how ear infections happen and what triggers them. Understanding the causes can help you prevent them and take the proper steps for quick relief. Let’s dive in!

How Does an Ear Infection Happen?

Around 90% of ear infections occur in the middle ear and are known as otitis media. These infections are usually secondary because they are usually triggered by nasal issues like the common cold or chronic sinusitis.

Otitis Media – The Most Common Type of Ear Infection

Otitis media is an infection of the middle ear and is the most frequently occurring type of ear infection. It often results from issues in the nose due to the anatomical connection between the two areas.

How the Middle Ear Works?

The middle ear is an air-filled cavity located just behind the eardrum. It contains three tiny bones that are essential for hearing. For the eardrum to vibrate properly and transmit sound clearly, the air pressure in the middle ear must match the pressure outside the ear. This balance is maintained by a narrow passage called the eustachian tube, which connects the middle ear to the back of the nose (nasopharynx).

The Role of the Eustachian Tube

The eustachian tube plays a key role in regulating ear pressure and draining fluid from the middle ear. When it becomes blocked or inflamed—often due to a cold, sinus infection, or allergies—it can’t function properly. This causes a pressure imbalance and may lead to fluid buildup in the middle ear.

How does Middle Ear Infection Happen?

As mentioned earlier, our ear is connected to the back of the nose through the Eustachian tube. This means any infection in the nose can easily spread to the Eustachian tube, potentially leading to an ear infection.

Mucus from a Cold Can Block the Tube

During a cold, the nose produces excessive mucus, which drains toward the back of the nasal cavity. Thick mucus can block the eustachian tube, causing negative pressure in the middle ear. Thin mucus, on the other hand, may seep into the middle ear and carry pathogens that trigger an infection.

Forceful Nose Blowing During a Cold

Blowing your nose too hard—especially when one nostril is blocked—creates high pressure in the nasal passage. This pressure can push infected mucus from the nose into the middle ear through the eustachian tube, leading to an infection.

Chronic sinusitis causing ear issues

In chronic sinusitis, mucus continuously drains from the sinuses to the back of the nose. If the mucus is thick, it can block the eustachian tube, resulting in pressure changes and fluid buildup in the middle ear. If the mucus is thin and infected, it may enter the middle ear directly and cause infection.

Sudden changes in air pressure

Rapid changes in air pressure can disturb the balance between the outer and middle ear. This happens during:

1. Airplane takeoff and landing

2. High-speed elevators in tall buildings

3. Deep-sea diving

4. Bungee jumping

5. Skydiving

If the eustachian tube is already inflamed or partially blocked, these pressure shifts can further restrict airflow, leading to fluid buildup and possible infection.

Allergies and Eustachian Tube Blockage

Allergies can cause swelling in the mucous lining of the eustachian tube, leading to blockage. This blockage results in negative pressure, causing fluid buildup in the middle ear, which can lead to an infection.

Spread of Infection from Other Parts of the Ear

While rare, infections from other parts of the ear—such as the outer ear (otitis externa) or inner ear—can spread to the middle ear. However, in most cases, ear infections begin in the middle ear and may spread outward if left untreated.

Otitis Externa – Infection of the Outer Ear Canal

Otitis externa, also known as an external ear infection, occurs in the ear canal and is the second most common type of ear infection after otitis media. This condition often develops due to external irritants or infections and can be bacterial or fungal. Here are the common ways otitis externa (including swimmer’s ear and otomycosis) can occur:

Scratches from Cleaning the Ears

Inserting cotton buds, pins, or other objects into the ear to clean it can damage the delicate ear canal lining. When the ear is already moist—or if the object is unclean—this damage increases the risk of infection. These scratches can lead to diffuse otitis externa, which may be caused by bacteria or fungi (otomycosis).

Water Exposure Weakens Skin Protection

Water trapped in the ear canal softens the skin, making it fragile and more prone to deep scratches. These micro-injuries on wet skin easily get infected, leading to bacterial or fungal otitis externa, especially in warm or humid climates.

Swimmer’s Ear from Frequent Pool Exposure

Regular swimming—especially in chlorinated pools—can irritate and dry out the ear canal, damaging its natural defense barrier. This often leads to chronic otitis externa, commonly known as swimmer’s ear.

Boils in the Ear (Furuncle in ear)

The outer ear canal contains hair follicles, which can become infected by Staphylococcus aureus. This results in painful boils near the entrance of the ear canal. This type of localized infection is referred to as furunculosis.

Fungal Ear Infections from Oil (Otomycosis)

Applying oil in the ear—especially when done regularly—can promote the growth of fungi by providing a nutrient-rich environment. This leads to otomycosis, a fungal ear infection marked by severe itching, discomfort, and discharge.

Complications from Unprescribed Ear Drops

Over-the-counter (OTC) or unprescribed antibacterial ear drops without proper medical guidance can worsen the problem. These drops may kill off healthy bacteria and allow fungi to grow unchecked, increasing the risk of a fungal ear infection. In more serious cases, incorrect usage can cause a perforated eardrum, which may require surgical repair through a procedure called tympanoplasty.

Otitis Interna – The Rarest and Most Serious

Otitis interna affects the innermost part of the ear and is the rarest but most dangerous type of ear infection. It spreads rapidly due to poor immune defense in this area and can cause permanent damage if not treated promptly.

It is always secondary and usually results from:

1. Middle ear infections (Otitis Media)

2. Brain infections

Neglected otitis media is a common cause. Due to close proximity, the infection can spread both to and from the brain and middle ear.

Conclusion

Ear infections can arise from various triggers—ranging from common colds and allergies to water exposure and pressure changes. While middle ear infections (otitis media) are the most common, infections of the outer (otitis externa) and inner ear (otitis interna) can also occur and may lead to serious complications if left untreated. Understanding how these infections develop can help you take preventive measures and seek timely medical care. Whether it’s managing nasal health, avoiding risky ear-cleaning habits, or protecting your ears during activities, small steps can go a long way in keeping your ears healthy and infection-free.

Dr. K. R. Meghanadh