This retrospective cohort study investigates the effectiveness and safety of extended anaerobic coverage (EAC) compared to limited anaerobic coverage (LAC) in treating community-acquired aspiration pneumonia. The study included 3,999 patients admitted to 18 hospitals in Ontario, Canada, from 2015 to 2022. Patients were categorized into LAC and EAC groups based on their initial antibiotic therapy. The primary outcome was in-hospital mortality, while secondary outcomes included the incidence of *Clostridioides difficile* colitis. Key findings: - In-hospital mortality was similar between the LAC and EAC groups (30.3% vs 32.1%). - The adjusted risk difference for in-hospital mortality was 1.6% (95% CI, -1.7% to 4.9%). - The adjusted risk difference for *C difficile* colitis was 1.0% (95% CI, 0.3% to 1.7%). Interpretation: Extended anaerobic coverage did not provide additional benefits in terms of mortality and was associated with a higher risk of *C difficile* colitis. This suggests that LAC is sufficient for treating community-acquired aspiration pneumonia, reducing the risk of antibiotic adverse effects and potential harm. The study supports the current guidelines recommending against routine addition of anaerobic coverage in such cases.This retrospective cohort study investigates the effectiveness and safety of extended anaerobic coverage (EAC) compared to limited anaerobic coverage (LAC) in treating community-acquired aspiration pneumonia. The study included 3,999 patients admitted to 18 hospitals in Ontario, Canada, from 2015 to 2022. Patients were categorized into LAC and EAC groups based on their initial antibiotic therapy. The primary outcome was in-hospital mortality, while secondary outcomes included the incidence of *Clostridioides difficile* colitis. Key findings: - In-hospital mortality was similar between the LAC and EAC groups (30.3% vs 32.1%). - The adjusted risk difference for in-hospital mortality was 1.6% (95% CI, -1.7% to 4.9%). - The adjusted risk difference for *C difficile* colitis was 1.0% (95% CI, 0.3% to 1.7%). Interpretation: Extended anaerobic coverage did not provide additional benefits in terms of mortality and was associated with a higher risk of *C difficile* colitis. This suggests that LAC is sufficient for treating community-acquired aspiration pneumonia, reducing the risk of antibiotic adverse effects and potential harm. The study supports the current guidelines recommending against routine addition of anaerobic coverage in such cases.