What is the best antibiotic for an upper respiratory tract infection (URTI)?

Most Upper Respiratory Tract Infections Do Not Require Antibiotics

The vast majority of upper respiratory tract infections (URTIs) are viral and should be managed with supportive care alone—antibiotics cause more harm than benefit in these cases. 1

When Antibiotics Are NOT Indicated

• Most URTIs are viral and occur above the vocal cords with normal pulmonary auscultation, making antibiotics inappropriate and potentially harmful 1
• Do not prescribe antibiotics for: common cold, influenza, COVID-19, laryngitis, or acute bronchitis in otherwise healthy adults 1, 2
• Even when fever is present in acute bronchitis, antibiotics are not indicated unless fever >38°C persists for more than 3 days 3

When Antibiotics ARE Indicated

Acute Bacterial Rhinosinusitis (ABRS)

Amoxicillin-clavulanate is the first-line antibiotic when treatment is warranted 1, 4

Antibiotics are appropriate when patients meet ANY of these criteria:

• Symptoms persisting >10 days without improvement 1
• Severe symptoms: fever >39°C with purulent nasal discharge or facial pain for ≥3 consecutive days 1
• "Double sickening": worsening after initial improvement following a typical viral URI 1
• Unilateral or bilateral infraorbital pain that increases when bending forward, pulsatile pain peaking in early evening/night, or failure of initial symptomatic treatment 1

Dosing for ABRS:

• Adults: 875 mg/125 mg every 12 hours OR 500 mg/125 mg every 8 hours for 7-10 days 5, 4
• Children: 80-100 mg/kg/day (amoxicillin component) divided into three doses 1

Streptococcal Pharyngitis

• Amoxicillin is first-line treatment for confirmed Group A beta-hemolytic streptococcal pharyngitis 1
• Treatment duration: 10 days to prevent acute rheumatic fever 1
• Use Centor criteria or rapid antigen testing to distinguish bacterial from viral pharyngitis 6

Acute Otitis Media (AOM)

• Immediate antibiotics indicated for: children <2 years, children >2 years with marked symptoms, bilateral AOM with otorrhea 1
• Amoxicillin-clavulanate provides coverage against beta-lactamase-producing H. influenzae and M. catarrhalis 1, 6
• Watchful waiting with reassessment after 48-72 hours is reasonable for children >2 years without severe symptoms 1

Alternative Antibiotics (When Amoxicillin-Clavulanate Cannot Be Used)

Second-line options for ABRS:

• Second-generation cephalosporins: cefuroxime-axetil 1
• Third-generation cephalosporins: cefpodoxime-proxetil, cefotiam-hexetil (but NOT cefixime) 1
• Doxycycline 1
• Respiratory fluoroquinolones: levofloxacin or moxifloxacin 1

Critical Pitfalls to Avoid

• Never use first-generation cephalosporins (like cephalexin) for respiratory infections—they have inadequate activity against S. pneumoniae with decreased penicillin susceptibility 1
• Avoid ciprofloxacin, ofloxacin, and cefixime—they lack adequate pneumococcal coverage 1
• Do not assume all cephalosporins are equivalent—second and third-generation agents have significantly better respiratory pathogen coverage than first-generation drugs 1

Supportive Care Measures (Always Appropriate)

• Analgesics for pain 1
• Antipyretics for fever 1
• Saline nasal irrigation 1
• Intranasal corticosteroids for symptom relief 1
• Systemic or topical decongestants as needed 1

Monitoring and Reassessment

• Assess therapeutic efficacy after 2-3 days of antibiotic treatment 1, 5
• Fever should resolve within 24 hours for pneumococcal infections and 2-4 days for other bacterial etiologies 1
• If no improvement by 72 hours, consider clinical and radiological reassessment, possible hospitalization, or antibiotic switch 1
• Cough may persist longer and should not be used as the sole indicator of treatment failure 1