The lungs, like other organs in the body, can be infected by bacteria and become inflamed and septic. The lungs are a vital organ of the body, connected to the outside world, and although they are fairly protected, they are sometimes immune to infection. A lung abscess is when the lung becomes septic and forms a cavity and pus. At first, the lung may become infected with bacteria and inflammation, and the patient may have high fever and cough; later, necrosis begins in the center of the lesion, and when the necrotic tissue breaks down and enters the bronchus, a cavity is formed, at which time the patient will cough up a lot of pus-smelling sputum and the body temperature will drop. Most acute lung abscesses can be cured by medication, but if the treatment is not timely and thorough, it may turn into chronic lung abscesses, and then surgery is needed. Lung abscess mostly occurs in young adults, more men than women, and acute aspiration lung abscess has an acute onset (there may be misaspiration before the onset), and the patient has chills and fever, and the temperature may be as high as 39-40 degrees; accompanied by cough, coughing mucus sputum or mucopurulent sputum; inflammation spread to local pleura may cause chest pain; when the lesion is large, shortness of breath may occur; in addition, there may be mental weakness, fatigue and poor appetite. After about 7-10 days, the cough intensifies, the abscess breaks into the bronchi, and a large amount of pus-smelling sputum is coughed up, which can reach 300-500 ml per day, at which time the body temperature drops. Since the pathogenic bacteria are mostly anaerobic, the sputum has a fishy odor. Sometimes there is blood in the sputum and even fresh blood. Hematogenous pulmonary abscesses mostly start with systemic sepsis manifestations such as chills and high fever caused by the primary lesion (outside the lungs), and pulmonary symptoms such as cough and sputum appear only after a few days to two weeks. Usually the sputum volume is small, and hemoptysis is very rare. Patients with chronic lung abscess have chronic cough, coughing sputum, recurrent hemoptysis, secondary infection and irregular fever, and often have chronic wasting pathology such as anemia and wasting.