Antibiotic Course Duration for Lower Respiratory Tract Infections

For uncomplicated community-acquired LRTIs managed at home, treat for 5-7 days with amoxicillin as first-line therapy. 1, 2

Treatment Duration by Clinical Setting

Standard duration is 5-7 days for most uncomplicated LRTIs including acute bronchitis and mild community-acquired pneumonia 1, 2
Patients should be instructed to return if fever does not resolve within 48 hours or if symptoms persist beyond 3 weeks 1, 2
Clinical improvement should be expected within 3 days of starting antibiotics 1, 2

Minimum 5 days of therapy is recommended for community-acquired pneumonia, with treatment extending beyond 5 days only if the patient has not achieved clinical stability 3
Clinical stability criteria include: resolution of vital sign abnormalities, ability to eat, and normal mentation 3
Switch from IV to oral therapy should occur by day 3 if the patient is clinically stable 1

Legionella pneumophila: Extended treatment of 21 days with a macrolide plus rifampicin is recommended 2, 3
Staphylococcus aureus pneumonia: 14-21 days of treatment 3
Gram-negative enteric bacilli: 14-21 days of treatment 3

5 days of antibiotic therapy is the standard duration for COPD exacerbations with bacterial infection 3
Treatment should not exceed 8 days in a responding patient 3
Antibiotics are indicated only for Type I Anthonisen exacerbations (all three cardinal symptoms: increased dyspnea, sputum volume, and purulence) or Type II with purulence 1

Hospitalized patients: Reassess at day 2-3 for clinical response including fever resolution and lack of progression of pulmonary infiltrates 1, 3
Outpatient patients: Reassess at day 5-7 if no improvement 3
Fever should resolve within 2-3 days after initiating treatment 3

After 3 days without improvement, consider alternative diagnoses or complications rather than automatically extending antibiotic duration 1, 3
Full microbiological reassessment should be performed in unstable patients who fail initial therapy 1
Change to an antibiotic with broader coverage (including Pseudomonas aeruginosa and resistant Streptococcus pneumoniae) if treatment fails 1

Do not extend treatment beyond 7 days for uncomplicated LRTI without specific indication, as this increases adverse effects without improving outcomes 1, 2, 3
Do not prescribe antibiotics for viral bronchitis in otherwise healthy adults, as most LRTIs are self-limiting 2
Do not use prophylactic antibiotics in patients with chronic bronchitis or COPD for prevention of exacerbations 1
Cough may persist longer than the duration of antibiotic treatment and does not indicate treatment failure 1