Pneumonia continues to be the main cause of death due to infection in the world, and it produces a high consumption of healthcare resources. The guidelines established by the scientific societies improve the care of patients with pneumonia. One way of evaluating the effect of the guidelines is to analyze their impact on the prognosis of the infection. To evaluate this effect, cohort studies have been performed using before-after, observational, cost-effectiveness, and, to a lesser degree, randomized designs. The most recent studies show that the implementation of the guidelines is accompanied by an increase in the process of care percentage and a lower inpatient hospital mortality rate- including the first 48 hours and after 30 days. These findings are consistent across various studies, and they have been confirmed in patients admitted to the intensive care unit. Clinical stability is also reached earlier in patients hospitalized for community-acquired pneumonia (CAP) when the antibiotic treatment is begun early and complies with the recommendations. Finally, the choice of antibiotics that adhere to the guidelines is cost-effective in CAP requiring hospitalization, which is responsible for 80% of the total cost of this disease.