What is the recommended treatment for a 16-year-old male with sinusitis?

Treatment of Sinusitis in a 16-Year-Old Male

First-Line Antibiotic Therapy

For a 16-year-old male with acute bacterial sinusitis, start with amoxicillin 45 mg/kg/day divided into 2 doses (or 500 mg twice daily) for 10-14 days, or use high-dose amoxicillin-clavulanate 875 mg/125 mg twice daily if the patient has risk factors such as recent antibiotic use, daycare attendance, or lives in an area with high rates of resistant Streptococcus pneumoniae. 1

When to Start Antibiotics

Before prescribing antibiotics, confirm the diagnosis meets one of three bacterial patterns 1:

• Persistent pattern: Nasal discharge or daytime cough lasting ≥10 days without improvement 2, 1
• Severe pattern: Fever ≥39°C for ≥3 consecutive days with thick, purulent nasal discharge 2, 1
• Worsening pattern: Initial improvement from viral URI followed by worsening symptoms within 10 days 1, 3

Watchful Waiting Option

For mild persistent symptoms without severe features, consider offering 3 additional days of observation before starting antibiotics 2. This approach balances avoiding unnecessary antibiotic use (number needed to harm = 3) against the benefit of treatment (number needed to treat = 3-5) 2.

Antibiotic Selection Algorithm

Standard First-Line (No Risk Factors)

• Amoxicillin 45 mg/kg/day divided twice daily for 10-14 days 1
• For a typical 16-year-old (~60 kg), this equals approximately 500 mg twice daily 1

High-Risk First-Line

Use high-dose amoxicillin-clavulanate 875 mg/125 mg twice daily if the patient has 1, 4:

• Age <2 years (not applicable here, but relevant for younger siblings)
• Recent antibiotic use within past 4-6 weeks
• Daycare attendance
• High local prevalence of resistant S. pneumoniae

Treatment Monitoring and Failure Protocol

Reassess at 72 hours: If symptoms are worsening or not improving, switch to high-dose amoxicillin-clavulanate (875 mg/125 mg twice daily) 2, 1. This timepoint is critical—continuing ineffective therapy beyond 72 hours delays appropriate treatment 1.

Second-Line Options After Treatment Failure

If the patient fails amoxicillin-clavulanate after 72 hours, switch to 1, 5:

• Respiratory fluoroquinolone: Levofloxacin 500 mg once daily for 10-14 days (90-92% predicted efficacy) 1, 5
• Third-generation cephalosporin: Cefpodoxime or cefdinir 1, 5
• Intramuscular ceftriaxone: 50 mg/kg (up to 1-2 g) once daily for 5 days if unable to tolerate oral medications 1, 5

Adjunctive Therapies (Strongly Recommended)

These therapies improve outcomes regardless of antibiotic choice 1, 3:

• Intranasal corticosteroids: Mometasone, fluticasone, or budesonide twice daily to reduce mucosal inflammation 1, 3
• Saline nasal irrigation: Promotes mucus clearance and reduces tissue edema 1, 3
• Analgesics/antipyretics: Acetaminophen or ibuprofen for pain and fever relief 1, 3

Therapies to AVOID

Do NOT use the following due to insufficient evidence or potential harm 1:

• Oral or topical decongestants (may thicken secretions)
• Antihistamines (unless concurrent allergic rhinitis is present)
• Mucolytics

Penicillin Allergy Considerations

If the patient has a documented penicillin allergy 1, 5:

• Non-severe allergy (rash): Use second- or third-generation cephalosporins (cefuroxime, cefpodoxime, or cefdinir) 1, 5
• Severe Type I hypersensitivity (anaphylaxis): Use respiratory fluoroquinolone (levofloxacin 500 mg once daily for 10-14 days) 1, 5

Never use azithromycin due to resistance rates exceeding 20-25% for both S. pneumoniae and H. influenzae 1, 5.

Red Flags Requiring Urgent Evaluation

Watch for complications that require immediate imaging (contrast-enhanced CT) and possible hospitalization 2:

• Orbital complications: Periorbital swelling, proptosis, impaired extraocular muscle function, or visual changes 2
• CNS complications: Severe headache, photophobia, seizures, altered mental status, or focal neurologic findings 2
• High fever unresponsive to antipyretics 1

These complications have higher morbidity and mortality than uncomplicated sinusitis and require urgent ENT or neurosurgical consultation 2.

Treatment Duration and Expected Timeline

• Standard duration: 10-14 days or until symptom-free for 7 days 1, 5
• Expected improvement: Most patients show noticeable improvement within 3-5 days of appropriate antibiotic therapy 1, 5
• Complete resolution: Typically occurs by 10-14 days 1, 5

If no improvement occurs by 7 days despite appropriate second-line therapy, refer to otolaryngology for further evaluation 2, 1.

Critical Pitfalls to Avoid

• Do not prescribe antibiotics for symptoms <10 days unless severe pattern is present (fever ≥39°C with purulent discharge for ≥3 days) 1, 3
• Do not continue ineffective antibiotics beyond 72 hours—this delays appropriate treatment and allows complications to develop 1
• Do not use first-generation cephalosporins (cephalexin) due to inadequate coverage against H. influenzae 5, 6
• Do not use clindamycin as monotherapy—it lacks activity against H. influenzae and M. catarrhalis 5