Otitis externa (OE) refers to inflammation or infection of the skin of the external auditory canal, which is the passage from the outer ear to the eardrum. This condition may also affect the outer ear structures such as the pinna or tragus. It is commonly known as swimmer’s ear because exposure to water and humidity often precedes the illness, although water exposure is not always necessary for the condition to develop. OE can be acute, typically lasting less than six weeks, or chronic, persisting for more than three months. The inflammation may be infectious or non-infectious and related to skin conditions such as eczema or psoriasis.
Why Does Otitis Externa Occur?
The external auditory canal is a narrow, skin-lined passage containing hair follicles and cerumen-producing glands. Cerumen helps maintain an acidic environment that inhibits microbial growth and protects the canal from irritation. When this protective barrier is disrupted by moisture retention, mechanical trauma, or underlying skin disease, the risk of inflammation and infection increases. Prolonged moisture exposure raises the pH of the canal and promotes bacterial proliferation.
How Can Otitis Externa Be Classified?
Otitis externa can be classified into several forms. Acute diffuse otitis externa is the most common presentation. Acute localized otitis externa involves infection of a single hair follicle. Chronic otitis externa persists for more than six weeks and is often associated with dermatologic disorders. Necrotizing otitis externa is a rare but severe form that extends beyond the ear canal and occurs mainly in immunocompromised individuals.
What Are the Primary Risk Factors for Developing Otitis Externa ?
Several factors increase an individual’s susceptibility to otitis externa. Moisture is the most significant risk factor. Frequent swimming, especially in water with high bacterial counts, or living in humid climates can cause the skin of the ear canal to soften and break down. This moisture provides an ideal breeding ground for pathogens. Mechanical trauma is another frequent cause. Many individuals attempt to clean their ears using cotton swabs, hairpins, or other small objects. This practice often pushes cerumen deeper into the canal and creates microscopic abrasions in the skin, providing an entry point for bacteria. Additionally, underlying dermatological conditions such as eczema, psoriasis, or seborrheic dermatitis can cause the skin to flake and crack, increasing the likelihood of secondary infection. Finally, the use of devices that obstruct the ear canal, such as hearing aids or tight-fitting earbuds, can trap moisture and irritate the lining of the canal.
How Is Otitis Externa Diagnosed?
Diagnosis is primarily based on clinical history and a physical examination. A physician will look for signs of edema and erythema in the external canal. During the examination, the use of an otoscope is essential to visualize the state of the canal and, importantly, to ensure the tympanic membrane is intact. Distinguishing between otitis externa and otitis media, which is an infection of the middle ear, is crucial, as the treatments differ significantly.
The accuracy of the diagnosis has been significantly enhanced by advanced dermatoscopes like the IBOOLO DE-4100 PRO, which offers four specialized lighting modes—Non-polarized, Polarized, Amber Polarized, and UV light. Each mode provides unique insights into the state of the external auditory canal. DE-4100 PRO allow clinicians to capture clear, high-definition images of the ear canal. This level of detail is particularly helpful in identifying fungal infections, small abrasions, or subtle signs of chronic inflammation.
Is Otitis Externa Contagious Between Individuals?
A common misconception is that otitis externa is highly contagious, similar to "pink eye" or the common cold. However, otitis externa is generally not considered a contagious condition. The bacteria that cause the infection are often already present on the skin or in the environment (like in pool water). The infection occurs because of a change in the host's ear environment—such as excess moisture or skin trauma—rather than through direct person-to-person transmission. While you cannot "catch" swimmer's ear by sitting next to someone who has it, sharing contaminated items that enter the ear canal, such as earbuds or earplugs, is discouraged. Maintaining personal hygiene and avoiding the sharing of ear-related devices is sufficient to prevent the rare possibility of transferring pathogenic bacteria from one person to another.
What Is the Standard Treatment for Otitis Externa?
The management of otitis externa involves three main components: pain control, cleaning of the ear canal, and the application of topical medications. Since the pain can be significant, non-steroidal anti-inflammatory drugs (NSAIDs) or acetaminophen are often recommended. A crucial step in treatment is the "toilet" or cleaning of the ear canal. Removing purulent debris and cerumen allows topical medications to make direct contact with the infected skin. If the ear canal is so swollen that drops cannot enter, a clinician may insert an "ear wick"—a small piece of compressed sponge or gauze—that carries the medication into the deep canal. Topical therapy is the gold standard for treatment. These medications usually contain a combination of an antibiotic (such as a fluoroquinolone or an aminoglycoside) to kill the bacteria and a corticosteroid to reduce inflammation and itching. Acidifying drops, such as acetic acid solutions, may also be used in mild cases to restore the canal’s natural pH. Oral antibiotics are rarely necessary unless the infection has spread to the outer ear or if the patient is immunocompromised.