Lung infections are inflammation of the lungs that occurs as a result of attack by infectious agents. The key to the treatment of lung infections is to determine the likely causative organisms and their drug resistance, as well as the severity of the lung infection. Choosing the right antibiotic at the time of initial treatment can control the infection as quickly as possible. For young adults with lung infections without underlying disease, common pathogens include Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, and Chlamydia pneumoniae, which can be treated with penicillins, doxycycline, azithromycin, first- or second-generation cephalosporins, and roentgenolones. For elderly patients with underlying disease, common pathogens include Streptococcus pneumoniae, Haemophilus influenzae, gram-negative bacilli, Staphylococcus aureus, and Catamorium, which can be treated with second-generation cephalosporins alone or in combination with a macrolide, a laxative inhibitor alone or in combination with a macrolide, and a whooping quinolone. Antibiotic therapy is required for at least 5 days, 48 to 72 hours after normalization of body temperature. Treatment of lung infections requires the selection of appropriate antibiotics and initiation of therapy as soon as possible, taking into account the patient’s age, the presence of underlying disease, the setting of the infection, the possible causative organisms and drug resistance, and the severity of the lung infection.