The pathological changes of lobar pneumonia are divided into four phases: phase I is the congestive edema phase, phase II is the red hepatomegaly phase, phase III is the gray hepatomegaly phase, and phase IV is the dissolution and dissipation phase. The following is a description of the phase I congestive edema stage, which is 1-2 days into the disease and can be clinically characterized by coughing as the main symptom. The second stage is the red hepatomegaly stage, which is 2-4 days after the onset of the disease. The third stage is the gray hepatomegaly stage, which is 4-7 days of the disease. The main symptoms are still cough and sputum, but there is no rust-colored sputum, and the X-ray is the same as the red hepatomegaly stage. The fourth stage is the dissolution and dissipation stage, and the fourth stage is the imminent recovery and dissipation.