Otitis externa is an inflammation or infection of the ear canal, the roughly 2.5-centimeter tube that runs from the opening of your ear to your eardrum. Often called “swimmer’s ear,” it’s one of the most common ear problems, generating an estimated 2.4 million healthcare visits per year in the United States alone. That works out to about one in every 123 people affected annually, with direct healthcare costs approaching half a billion dollars.
What Happens Inside the Ear Canal
Your ear canal has a built-in defense system. The outer portion is lined with hair follicles and glands that produce earwax, which keeps the canal slightly acidic and coats the skin with a water-resistant barrier. This acidic environment discourages bacteria and fungi from gaining a foothold.
Otitis externa starts when something disrupts that protective layer. Once the canal’s natural pH shifts or the skin lining gets damaged, bacteria (most often Pseudomonas and Staphylococcus species) or fungi move in and trigger an inflammatory response. The canal swells, produces discharge, and becomes painful. In some cases, the inflammation spreads beyond the canal to the outer ear itself, including the visible flap (pinna) or the small cartilage bump in front of the canal opening (tragus).
Common Causes and Risk Factors
Water is the most frequent culprit. Swimming, showering, or any prolonged moisture exposure softens the canal’s protective skin lining and washes away earwax, creating a warm, damp environment where bacteria thrive. This is why the condition peaks in summer months and in people who swim regularly.
Mechanical trauma is the other major trigger. Inserting cotton swabs, earbuds, hearing aids, or fingers into the canal can scratch the delicate skin or strip away the wax barrier. Even aggressive ear cleaning with a towel can be enough. People with skin conditions like eczema or psoriasis are also more vulnerable because their canal skin is already compromised. Allergic reactions to hair products, earrings, or hearing aid materials can set off a non-infectious form of the condition.
What It Feels Like
The hallmark symptom is ear pain that worsens when you tug on your earlobe or press on the tragus. This is one of the quickest ways to distinguish otitis externa from a middle ear infection (otitis media), where pulling on the outer ear typically doesn’t hurt.
In mild cases, you may notice itching inside the canal, slight redness, and minor discomfort. As the infection progresses, pain intensifies and the canal starts producing a clear or yellowish discharge. The ear may feel full or muffled because swelling narrows the canal. In severe cases, the canal swells shut almost entirely, pain radiates to the face or neck, lymph nodes near the ear become tender, and you may develop a fever. The outer ear can appear red and swollen.
Who Gets It Most
While more than half of all cases occur in adults over 20, the highest rates are in children. Kids aged 5 to 9 and 10 to 14 are diagnosed most frequently, likely because of time spent swimming. The condition affects people of all ages, though, and the CDC estimates that healthcare providers spend roughly 600,000 hours per year on office visits for it.
How It’s Treated
The standard first-line treatment is topical ear drops, not oral antibiotics. Clinical practice guidelines are clear on this point: for uncomplicated otitis externa that hasn’t spread beyond the ear canal, systemic antibiotics (pills taken by mouth) should not be prescribed as initial therapy. Topical drops work better because they deliver medication directly to the infected tissue at much higher concentrations than an oral pill could achieve.
The drops typically contain an antibiotic, an anti-inflammatory steroid, or a combination of both. Some formulations use an acidifying agent to restore the canal’s natural pH. If you have a known or suspected hole in your eardrum or ear tubes, your provider will choose a formulation that’s safe for the middle ear.
When the canal is so swollen that drops can’t reach the infected area, a small sponge-like device called an ear wick may be placed inside. The wick absorbs the medication and expands gently against the canal walls, delivering the drops where they need to go. It’s typically removed or falls out on its own after a few days as the swelling subsides.
Most uncomplicated cases improve noticeably within 48 to 72 hours of starting drops and resolve fully within 7 to 10 days. During treatment, keeping the ear dry is essential. That means no swimming and protecting the ear during showers.
Otitis Externa vs. Middle Ear Infection
These two conditions are easy to confuse because both cause ear pain, but they involve completely different structures. Otitis externa is an infection of the ear canal, the passage leading to the eardrum. Otitis media is an infection behind the eardrum, in the air-filled middle ear space. The key clinical difference: with otitis externa, pressing on the tragus or pulling the earlobe reproduces or worsens pain. With a middle ear infection, it generally doesn’t. Middle ear infections also tend to follow colds or upper respiratory infections, while otitis externa is more closely tied to water exposure or canal trauma.
When Otitis Externa Becomes Dangerous
In rare cases, the infection can spread from the ear canal into the surrounding bone at the base of the skull. This aggressive form, called malignant or necrotizing otitis externa, is not a cancer despite the name. It’s a deep bone infection (osteomyelitis) that can be life-threatening if not caught early.
The condition predominantly affects older adults with diabetes and people with weakened immune systems, including those with HIV, cancer, or a history of radiation therapy to the head and neck. In one large study, 74.6% of patients with malignant otitis externa had diabetes, and the disease most commonly affected patients over 84 years old.
The warning signs are distinct from ordinary swimmer’s ear. Pain is severe and often worse at night, persisting or worsening despite appropriate antibiotic ear drops. Discharge continues, and a provider looking into the canal may see granulation tissue, a sign of aggressive inflammation, at the junction between the cartilage and bone portions of the canal. As the infection advances through the skull base, it can damage nearby cranial nerves, causing facial drooping, difficulty swallowing, hoarseness, or tongue weakness depending on which nerves are involved. The infection can progress through the temporal bone to reach the jaw joint, the base of the skull, and even the blood vessel channels (dural sinuses) near the brain.
If you have diabetes or a compromised immune system and develop ear pain that doesn’t improve with treatment within a few days, that warrants prompt evaluation. Early diagnosis changes outcomes significantly.
Preventing Swimmer’s Ear
Most cases are preventable with a few habits. The CDC recommends keeping ears as dry as possible during and after water exposure:
- Use ear protection when swimming. Earplugs, a bathing cap, or custom-fitted swim molds all help keep water out of the canal.
- Dry ears thoroughly after swimming or showering. Tilt your head to each side so the ear faces downward, letting gravity pull water out. Pull the earlobe in different directions while the ear is facing down to help drain trapped water.
- Use a hair dryer on the lowest heat and fan setting held several inches from the ear if water remains after tilting and toweling.
- Leave earwax alone. It’s there for a reason. Avoid inserting cotton swabs or other objects into the canal.
Over-the-counter ear-drying drops (typically alcohol-based or acidifying solutions) can help evaporate residual water after swimming. These should not be used if you have ear tubes, a perforated eardrum, an active ear infection, or any ear drainage.