In immunocompetent adults, common pneumonia usually resolves gradually in about 10-14 days with oral or intravenous broad-spectrum antibiotics. However, in immunocompromised young adults or older adults, or in patients with strong virulence of the infecting agent, or in patients with other chronic lung diseases, there is a possibility that common pneumonia may progress to severe pneumonia. In this case, patients need to be hospitalized as soon as possible to improve inflammatory parameters, chest CT and other tests to assess the severity of the disease, and be treated with more advanced broad-spectrum antibiotics or precise antibiotics, depending on the situation.