Symptoms that do not improve after 72 hours of initial treatment or that improve once and then worsen are considered ineffective, with the following common causes and management: 1. Failure of currently used drugs to cover or bacterial resistance, evaluation with laboratory sputum culture results, prudent adjustment of anti-infective drugs, and repeat pathogenic tests. Zhang Shaofu, Department of Respiratory Medicine, Shandong Qianfo Mountain Hospital, Shandong Province, China 2. Infections of specific pathogens such as Mycobacterium, fungi, Pneumocystis and viruses including SARS and avian influenza or endemic infections. Possible diagnostic techniques should be used to clarify the etiologic diagnosis and adjust the treatment.3. Complications such as pus thorax, migratory lesions or the presence of host factors of immune impairment are present.4. When the CAP diagnosis itself is wrong, the diagnosis should be re-verified to clarify whether it is due to other etiologies.