For how many days should antibiotic therapy be given for community-acquired pneumonia?

Antibiotic Duration for Community-Acquired Pneumonia

For uncomplicated community-acquired pneumonia, antibiotic therapy should be administered for a minimum of 5 days, with discontinuation when the patient has been clinically stable for 48-72 hours. 1

Standard Duration by Clinical Scenario

Uncomplicated CAP

• 5-7 days is the recommended duration for uncomplicated community-acquired pneumonia in both outpatient and hospitalized settings 2, 1
• Treatment can be stopped after a minimum of 5 days if the patient has been clinically stable for 48-72 hours 1, 3
• The most recent 2025 guidelines support even shorter courses: 3 days for non-severe or moderate CAP if clinically stable at day 3, 5 days if stability achieved by day 5 4

Classical Bacterial Infection

• 7-10 days for classical bacterial infection or uncomplicated CAP managed in the hospital 2

Specific Pathogen-Directed Therapy

• 10-14 days for suspected or proven Mycoplasma pneumoniae or Chlamydia pneumoniae infection 2
• 21 days for suspected or proven Legionella pneumophila or Staphylococcus aureus infection 2
• 21 days for severe CAP requiring ICU admission 2

Clinical Stability Criteria

Clinical stability must be assessed to guide treatment duration and is defined by: 1

• Resolution of vital sign abnormalities (temperature ≤37.8°C for 48 hours, respiratory rate <24 breaths/min, heart rate <100 bpm, systolic blood pressure ≥90 mmHg) 3
• Ability to eat and maintain oral intake 1
• Normal mentation 1
• No more than 1 CAP-associated sign of clinical instability 3

Fever should resolve within 2-3 days after initiation of antibiotic treatment 2. Failure to achieve clinical stability within 5 days warrants assessment for resistant pathogens, evaluation for complications (empyema, lung abscess, cavitation), and investigation for alternative diagnoses 1.

Evidence Supporting Shorter Courses

The shift toward shorter antibiotic courses is supported by high-quality evidence:

• A 2016 multicenter randomized trial demonstrated that 5-day treatment (when clinically stable) achieved clinical success rates of 91.9% at day 30, non-inferior to physician-determined longer courses 3
• A 2007 meta-analysis of 15 randomized trials (2,796 patients) found no difference in clinical failure rates between short-course (≤7 days) and extended-course (>7 days) regimens (RR 0.89,95% CI 0.78-1.02) 5
• The most recent 2025 evidence validates 3-day treatment for patients achieving clinical stability at day 3 4

Route of Administration

Switch from intravenous to oral antibiotics when fever has resolved and clinical condition is stable 2. This typically occurs after an average of 7-8 days of IV therapy in hospitalized patients, though earlier switches are appropriate when stability criteria are met 6.

Common Pitfalls to Avoid

• Do not continue antibiotics beyond necessary duration without clinical indication 1
• Do not fail to assess for clinical stability to guide treatment decisions 1
• Do not ignore pathogen-specific treatment durations when a causative organism is identified 1
• Do not treat for extended periods based solely on radiographic findings, as infiltrates may persist despite clinical resolution 2

Situations Requiring Longer Treatment

Extend treatment duration beyond 7 days for: 2, 1

• Pneumonia complicated by meningitis, endocarditis, or other deep-seated infections
• Pulmonary abscess, cavitation, or necrotizing pneumonia
• Empyem or significant pleural effusion
• Initial therapy that was not active against the identified pathogen
• Immunosuppression or cystic fibrosis