Amoxicillin Dosage for Adult Ear Infections
For adults with ear infections (acute otitis media), the recommended dosage of amoxicillin is 500 mg twice daily or 875 mg twice daily, depending on the severity of infection. 1
First-Line Treatment Options
- Amoxicillin is the first-line antibiotic treatment for ear infections in adults due to its effectiveness against common pathogens, safety profile, low cost, and narrow antimicrobial spectrum 1
- For mild to moderate ear infections: 500 mg every 12 hours (twice daily) 1
- For severe ear infections: 875 mg every 12 hours (twice daily) 1
- Treatment duration should be 7-10 days, with a minimum of 48-72 hours beyond symptom resolution 1
Rationale for Amoxicillin Selection
- Amoxicillin has excellent activity against Streptococcus pneumoniae, which is one of the most common bacterial pathogens in ear infections 2
- The drug achieves adequate middle ear fluid concentrations to treat most susceptible pathogens 3
- Amoxicillin is generally considered the most active of all oral β-lactams against streptococci, including pneumococci 2
Alternative Options for Penicillin-Allergic Patients
For patients with penicillin allergy, alternative treatments include:
- Cefdinir: 300 mg twice daily or 600 mg once daily 4
- Clarithromycin: 500 mg twice daily for 10 days 2
- Azithromycin: 500 mg on day 1, followed by 250 mg for 4 additional days 2
Treatment Failure Considerations
- If symptoms persist after 48-72 hours of amoxicillin therapy, the patient should be reevaluated 2
- Consider switching to amoxicillin-clavulanate (875 mg/125 mg twice daily) if treatment failure occurs, as this provides coverage for β-lactamase-producing organisms 2
- Beta-lactamase-producing Haemophilus influenzae is a common cause of treatment failure with amoxicillin alone 5
Special Considerations
- For patients who have received antibiotics in the previous 30 days, consider starting with amoxicillin-clavulanate instead of amoxicillin alone 2
- Patients with severe renal impairment (GFR 10-30 mL/min) should receive a reduced dose of 500 mg or 250 mg every 12 hours 1
- Take amoxicillin at the start of a meal to minimize gastrointestinal intolerance 1
Monitoring and Follow-up
- Reassess if there is no clinical improvement after 72 hours of therapy 4
- Complete the full course of antibiotics even if symptoms improve before completion 1
- For recurrent or persistent ear infections, consider referral to an otolaryngologist 6
Common Pitfalls to Avoid
- Underdosing amoxicillin may lead to treatment failure, especially with resistant strains of S. pneumoniae 5
- Unnecessary antibiotic treatment of viral upper respiratory infections should be avoided 2
- Failing to provide adequate analgesia alongside antibiotic therapy 6
- Not completing the full course of antibiotics, which may lead to recurrence or resistance 1