Recommended Antibiotics for Bacterial Sinusitis
Amoxicillin-clavulanate (high-dose: 875 mg/125 mg twice daily for adults; 90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate for children) is the preferred first-line antibiotic for acute bacterial sinusitis, providing optimal coverage against resistant bacteria including β-lactamase-producing organisms. 1, 2
First-Line Treatment Selection
Standard First-Line Therapy
High-dose amoxicillin-clavulanate is the preferred first-line agent for most patients with acute bacterial sinusitis, offering comprehensive coverage against Streptococcus pneumoniae (including drug-resistant strains), Haemophilus influenzae, and Moraxella catarrhalis 1, 2, 3
Plain amoxicillin (500 mg twice daily for mild disease; 875 mg twice daily for moderate disease) remains acceptable for uncomplicated cases without recent antibiotic exposure, but has limitations against β-lactamase-producing organisms 1, 4
For children, dosing depends on risk factors: standard-dose amoxicillin (45 mg/kg/day divided twice daily) for low-risk children ≥2 years, or high-dose amoxicillin-clavulanate (90 mg/kg/day of amoxicillin component with 6.4 mg/kg/day clavulanate) for high-risk children (age <2 years, daycare attendance, recent antibiotic use) 1, 2
Treatment Duration
Standard duration is 10-14 days or until symptom-free for 7 days, ensuring complete pathogen eradication 1, 2, 3
Shorter 5-7 day courses with certain agents (cephalosporins, fluoroquinolones) have comparable efficacy with fewer side effects for uncomplicated maxillary sinusitis 1, 5, 6
Penicillin-Allergic Patients
Non-Severe Allergy (Rash, Delayed Reactions)
Second- or third-generation cephalosporins are safe and effective alternatives for patients with non-Type I penicillin hypersensitivity 1, 2
Cefuroxime axetil (second-generation): provides good coverage against common pathogens 1, 7
Cefpodoxime, cefdinir, or cefprozil (third-generation): offer superior activity against H. influenzae compared to second-generation agents 1, 2, 7
The risk of cross-reactivity between penicillins and second/third-generation cephalosporins is negligible in non-severe allergies 1
Severe Allergy (Type I Hypersensitivity/Anaphylaxis)
Respiratory fluoroquinolones are the treatment of choice for patients with documented severe penicillin allergy 1, 2
Levofloxacin 500 mg once daily for 10-14 days (or 750 mg once daily for 5 days) provides 90-92% predicted clinical efficacy 1, 8
Moxifloxacin 400 mg once daily for 10 days offers equivalent coverage 1, 2
Second-Line Treatment for Failures
When to Switch Antibiotics
- Reassess at 72 hours (pediatrics) or 3-5 days (adults) - if no improvement or worsening symptoms, switch to second-line therapy 1, 2, 3
Second-Line Options
For patients failing amoxicillin monotherapy: switch to high-dose amoxicillin-clavulanate (4 g amoxicillin/250 mg clavulanate per day for adults) 1, 2
For patients failing amoxicillin-clavulanate: respiratory fluoroquinolones (levofloxacin or moxifloxacin) are the preferred second-line agents with 90-92% predicted efficacy against drug-resistant S. pneumoniae and β-lactamase-producing organisms 1, 2, 8
Ceftriaxone 1-2 g IM/IV once daily for 5 days (adults) or 50 mg/kg once daily (children) is appropriate for patients unable to tolerate oral medications or with severe disease 1, 2
Treatment Based on Anatomic Location
Maxillary Sinusitis (Most Common)
Standard first-line antibiotics (amoxicillin or amoxicillin-clavulanate) are appropriate 1
Symptoms include unilateral/bilateral infraorbital pain worsening when bending forward, pulsatile, peaking evening/night 1
Frontal, Ethmoidal, or Sphenoidal Sinusitis
Reserve fluoroquinolones (levofloxacin or moxifloxacin) for these locations due to potential for serious complications 1, 2
These sites require more aggressive therapy given proximity to critical structures 1
Antibiotics to AVOID
Azithromycin and Macrolides
Azithromycin should NOT be used for acute bacterial sinusitis due to resistance rates of 20-25% for both S. pneumoniae and H. influenzae 1, 2
French guidelines and the American Academy of Pediatrics explicitly exclude macrolides from recommended therapy 1
Trimethoprim-Sulfamethoxazole
- High resistance rates (50% for S. pneumoniae, 27% for H. influenzae) make this an inappropriate choice 1
Clindamycin Monotherapy
Never use clindamycin as monotherapy - it lacks activity against H. influenzae and M. catarrhalis, leading to 30-40% failure rates 1
Only appropriate when combined with a third-generation cephalosporin (cefixime or cefpodoxime) for treatment failures 1
Doxycycline
Has limited activity against H. influenzae with predicted bacteriologic failure rates of 20-25%, making it suboptimal when better alternatives exist 1
Not recommended for children <8 years due to tooth enamel discoloration risk 1
Adjunctive Therapies
Intranasal corticosteroids (mometasone, fluticasone, budesonide) twice daily reduce mucosal inflammation and improve symptom resolution - strongly recommended as adjunct to antibiotics 1, 2, 3
Short-term oral corticosteroids may be reasonable for patients with marked mucosal edema or failure to respond to initial treatment 1, 3
Saline nasal irrigation improves mucociliary clearance 1, 2, 3
Analgesics (acetaminophen, NSAIDs) for pain relief 1
Critical Pitfalls to Avoid
Do not prescribe antibiotics for viral rhinosinusitis - wait at least 10 days unless severe symptoms (fever ≥39°C with purulent discharge for ≥3 consecutive days) are present 1
Do not use mucus color alone to determine antibiotic need - color reflects neutrophils, not bacteria 1
Ensure adequate treatment duration (minimum 10 days for most agents) to prevent relapse and incomplete pathogen eradication 1, 2, 3
Reserve fluoroquinolones appropriately - avoid routine first-line use to prevent resistance development; use only for treatment failures, severe disease, or documented severe penicillin allergy 1, 2, 8
Complete the full antibiotic course even after symptoms improve to prevent relapse 1