Risk factors for acute cases include swimming, minor trauma from cleaning, using hearing aids and ear plugs, and other skin problems, such as psoriasis and dermatitis.

[2] Tenderness of pinna[6] is the predominant complaint and the only symptom directly related to the severity of acute external otitis.

Pushing the tragus, the tablike portion of the auricle that projects out just in front of the ear canal opening, also typically causes pain in this condition as to be diagnostic of external otitis on physical examination.

When enough swelling and discharge in the ear canal is present to block the opening, external otitis may cause temporary conductive hearing loss.

If the skin is healthy and uninjured, only exposure to a high concentration of pathogens, such as submersion in a pond contaminated by sewage, is likely to set off an episode.

[citation needed] The majority of cases are due to Pseudomonas aeruginosa and Staphylococcus aureus,[15] followed by a great number of other gram-positive and gram-negative species.

Touching or moving the outer ear increases the pain, and this maneuver on physical exam is important in establishing the clinical diagnosis.

It may be difficult to see the eardrum with an otoscope at the initial examination because of narrowing of the ear canal from inflammation and the presence of drainage and debris.

[citation needed] The diagnosis may be missed in most early cases because the examination of the ear, with the exception of pain with manipulation, is nearly normal.

As a moderate or severe case of external otitis resolves, weeks may be required before the ear canal again shows a normal amount of it.

In more severe or untreated cases, the infection can spread to the soft tissues of the face that surround the adjacent parotid gland and the jaw joint, making chewing painful.

In its mildest forms, otitis externa is so common that some ear nose and throat physicians have suggested that most people will have at least a brief episode at some point in life.

Inflammation of the ear canal skin typically begins with a physical insult, most often from injury caused by attempts at self-cleaning or scratching with cotton swabs, pen caps, fingernails, hair pins, keys, or other small implements.

[19][medical citation needed] Effective solutions for the ear canal include acidifying and drying agents, used either singly or in combination.

[20] When the ear canal skin is inflamed from the acute otitis externa, the use of dilute acetic acid may be painful.

Some contain antibiotics, either antibacterial or antifungal, and others are simply designed to mildly acidify the ear canal environment to discourage bacterial growth.

Although there is evidence that steroids are effective at reducing the length of treatment time required, fungal otitis externa (also called otomycosis) may be caused or aggravated by overly prolonged use of steroid-containing drops.

[22] Antibiotics by mouth are not a sufficient response to bacteria which cause this condition and have significant side effects including increased risk of opportunistic infection.

[22] Oral anti-pseudomonal antibiotics can be used in case of severe soft tissue swelling extending into the face and neck and may hasten recovery.

[citation needed] Effective medications include ear drops containing antibiotics to fight infection, and corticosteroids (Hydrocortisone +Neomycin+ Polymixin B) to reduce itching and inflammation.

Individuals with underlying diabetes, disorders of the immune system, or history of radiation therapy to the base of the skull are more likely to develop complications, including malignant otitis externa.

The hallmark of malignant otitis externa (MOE) is unrelenting pain that interferes with sleep and persists even after swelling of the external ear canal may have resolved with topical antibiotic treatment.

[23] It can also cause skull base osteomyelitis (SBO), manifested by multiple cranial nerve palsies, described below under the "Treatment" heading.

Paradoxically, the physical findings of MOE, at least in its early stages, are often much less dramatic than those of ordinary acute otitis externa.

[citation needed] Unlike ordinary otitis externa, MOE requires oral or intravenous antibiotics for cure.

Skull base osteomyelitis is a chronic disease that can require months of IV antibiotic treatment, tends to recur, and has a significant mortality rate.