Treatment of lung infections needs to be determined in relation to the patient’s age, the presence of previous major illnesses, and the location of the lung infection. For example, if the infection was contracted at home or in a hospital, the possible causative organisms and drug resistance will be different, and treatment needs to be started as soon as possible by choosing the appropriate antibiotic depending on the severity of the lung infection. Patients who are young and who have not had a previous major lung infection have common causative agents such as Mycoplasma pneumoniae, Chlamydia pneumoniae, Streptococcus pneumoniae, and Haemophilus influenzae. Treatment can be with penicillin, azithromycin, cefazolin, cefuroxime, levofloxacin, moxifloxacin, etc. In elderly and frail patients with previous serious diseases, the pathogens that commonly cause lung infections include Gram-negative bacilli, Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae, etc. Treatment can be with cefuroxime or cefuroxime combined with azithromycin, piperacillin or piperacillin combined with azithromycin, levofloxacin, moxifloxacin, etc. The key to the treatment of lung infection is to determine the possible causative organism and the drug resistance of that causative organism, as well as the severity of the lung infection. Initial treatment is important, and timely and correct treatment will yield twice the result with half the effort.