What is the appropriate first‑line ear‑drop therapy for an adult with acute otitis externa (swimmer’s ear) and an intact tympanic membrane?

First-Line Ear Drop Therapy for Acute Otitis Externa

For an adult with acute otitis externa and an intact tympanic membrane, prescribe any FDA-approved topical antimicrobial ear drop—all achieve 65–90% clinical cure within 7–10 days with no consistent superiority of one agent over another. 1

Topical Antimicrobial Selection

When the tympanic membrane is confirmed intact, your choice includes:

• Fluoroquinolone drops (ofloxacin 0.3% or ciprofloxacin 0.2% ± steroid) 1
• Aminoglycoside/polymyxin B combinations (neomycin/polymyxin B/hydrocortisone) 1, 2
• Acetic acid 2% (less expensive but may require longer treatment) 1

The addition of a corticosteroid component accelerates pain relief and reduces inflammation, making antibiotic-steroid combinations preferable to antibiotics alone. 1

Practical Selection Algorithm

Choose fluoroquinolone drops (ofloxacin 0.3% or ciprofloxacin 0.2%) when:

• Tympanic membrane integrity is uncertain or you cannot fully visualize it 1
• Patient has history of contact dermatitis, eczema, or chronic/recurrent otitis externa 1
• Patient has tympanostomy tubes or prior ear surgery 1

Choose neomycin/polymyxin B/hydrocortisone when:

• Tympanic membrane is definitively intact 1, 2
• Cost is a primary concern 1
• No history of neomycin sensitivity 1

Avoid neomycin-containing preparations entirely in patients with eczema, psoriasis, or any history of contact dermatitis—neomycin causes allergic reactions in 13–30% of patients with chronic otitis externa. 1

Essential Pre-Treatment Step: Aural Toilet

Before prescribing any ear drops, perform aural toilet to remove debris, cerumen, and inflammatory material—medication cannot penetrate through obstructing material to reach infected tissue. 1 Use gentle suction, dry mopping, or irrigation with body-temperature water or saline. 1

If severe canal edema prevents drop entry or you cannot visualize most of the tympanic membrane, place a compressed cellulose wick to facilitate drug delivery. 1 The wick expands when moistened and reduces canal edema while ensuring medication reaches the infected area. 1

Dosing and Administration Instructions

For Ofloxacin 0.3% (FDA-Approved Regimen)

Adults and children ≥13 years: 10 drops (0.5 mL) into the affected ear once daily for 7 days. 3

Administration technique (critical for efficacy):

1. Warm the bottle in your hand for 1–2 minutes to prevent dizziness 1, 3
2. Have the patient lie with the affected ear upward 1, 3
3. Instill drops to completely fill the ear canal 1
4. Apply gentle to-and-fro movement of the pinna or press the tragus in/out 4 times to eliminate trapped air 1, 3
5. Maintain this position for 5 minutes (use a timer) 1, 3

Only 40% of patients self-administer drops correctly during the first 3 days—having someone else apply the drops significantly improves adherence and outcomes. 1

For Other Topical Preparations

Most other FDA-approved preparations require twice-daily dosing for 7–10 days, following the same administration technique. 1, 2

Pain Management (Essential Component)

Prescribe appropriate analgesics based on pain severity:

• Mild-to-moderate pain: Acetaminophen 650–1000 mg every 6 hours or ibuprofen 400–600 mg every 6 hours 1
• Severe pain: Short-term opioid-containing analgesics for the first 48–72 hours 1

Inform patients that pain typically improves within 48–72 hours of starting topical therapy, regardless of which agent is used. 1, 4, 5

Do not prescribe topical anesthetic drops (benzocaine)—they are not FDA-approved for active infections and may mask treatment failure. 1

Treatment Duration

Prescribe drops for a minimum of 7 days, even if symptoms resolve earlier, to prevent relapse. 1 If symptoms persist beyond 7 days, continue drops until resolution for a maximum of 14 days total. 1

When Oral Antibiotics Are NOT Indicated

Do not prescribe oral antibiotics for uncomplicated acute otitis externa—topical therapy achieves cure rates of 77–96% versus only 30–67% for oral antibiotics, yet 20–40% of patients inappropriately receive oral antibiotics. 1

Reserve systemic antibiotics only for:

• Extension of infection beyond the ear canal (periauricular cellulitis or swelling) 1
• Diabetes mellitus or immunocompromised status 1
• Severe canal edema preventing adequate topical delivery despite wick placement 1
• Failure to improve after 48–72 hours of appropriate topical therapy 1

When systemic antibiotics are indicated, use fluoroquinolones (ciprofloxacin 500 mg twice daily) to cover Pseudomonas aeruginosa and Staphylococcus aureus, which cause approximately 98% of cases. 1

Patient Education Points

Instruct patients to:

• Keep the ear dry during treatment—cover with an earplug or petroleum jelly-coated cotton before showering 1
• Avoid swimming until infection resolves 1
• Do not insert cotton swabs or any objects into the ear canal 1
• Complete the full 7-day course even if symptoms resolve early 1
• Return for reassessment if symptoms do not improve within 48–72 hours or persist beyond 2 weeks 1

If the patient tastes the eardrops, they should inform you immediately—this indicates a tympanic membrane perforation requiring a switch to non-ototoxic fluoroquinolone drops. 1, 6

Reassessment Criteria

Reassess within 48–72 hours if no improvement occurs. 1 Common causes of treatment failure include:

• Inadequate drug delivery due to canal obstruction or poor adherence 1
• Allergic contact dermatitis from topical agents (especially neomycin or hydrocortisone) 1
• Fungal co-infection (otomycosis)—suspect if white fuzzy exudate with pruritus is present 1
• Incorrect diagnosis (chronic suppurative otitis media, necrotizing otitis externa, dermatologic disorder) 1

Critical Pitfalls to Avoid

• Prescribing oral antibiotics for uncomplicated cases 1
• Skipping aural toilet before drop administration 1
• Using neomycin-containing drops in patients with eczema or contact dermatitis history 1
• Inadequate pain management 1
• Failing to provide proper administration instructions 1
• Using ototoxic preparations when tympanic membrane integrity is uncertain 1, 6