What are the recommended antibiotic regimens for treating community-acquired pneumonia in different age groups?

Recommended antibiotic regimens for community-acquired pneumonia (CAP) by age group:

• Adults (including those aged 18 and over) with low-severity CAP: First-line treatment is oral amoxicillin 500 mg three times daily for 5 days (higher doses may be used as per BNF guidance). If penicillin allergy or amoxicillin is unsuitable (e.g., suspicion of atypical pathogens), alternatives include oral doxycycline (200 mg on day 1, then 100 mg once daily for 4 days), oral clarithromycin 500 mg twice daily for 5 days, or oral erythromycin 500 mg four times daily for 5 days (erythromycin preferred in pregnancy) ¹.
• Adults with moderate-severity CAP managed in the community: Oral amoxicillin 500 mg three times daily for 5 days plus oral clarithromycin 500 mg twice daily for 5 days if atypical pathogens are suspected. In penicillin allergy, doxycycline or clarithromycin alone are considered appropriate ¹.
• Young people aged 12–17 years with non-severe CAP: First choice is oral amoxicillin 500 mg three times daily for 5 days (dose adjustments per BNF for children). Alternatives if penicillin allergy or atypical pathogens suspected include oral clarithromycin 250–500 mg twice daily for 5 days, oral erythromycin 250–500 mg four times daily for 5 days, or oral doxycycline 200 mg on day 1 then 100 mg once daily for 4 days ¹.

Additional notes: Antibiotic choice is guided by activity against likely pathogens (notably Streptococcus pneumoniae), safety profile, and antimicrobial resistance risk. Amoxicillin is preferred for its targeted activity and tolerability. Macrolides and doxycycline cover atypical pathogens but have broader spectra and some safety considerations ¹.

Patients should be advised to seek medical advice if symptoms worsen rapidly, do not improve within 3 days, or if they become systemically very unwell. Expected symptom resolution timelines range from 1 week (fever resolution) to 6 months (full symptom resolution) ¹.