The most direct consequence of irrational use of antibacterial drugs is to increase the chance of adverse drug reactions, such as gastrointestinal reactions such as nausea and vomiting, allergic reactions such as rash or anaphylaxis, hematologic toxicity such as leukocytopenia, thrombocytopenia and abnormal coagulation, and damage to cardiac, hepatic and renal functions. Long-term use of broad-spectrum antibacterial drugs may cause dysbiosis and secondary secondary infections, including lethal Clostridium difficile infections. The most long-term effect is the induction of the emergence and colonization of drug-resistant flora that cannot be killed by previously used antimicrobial drugs under pressure of antimicrobial drug selection. Once immunocompromised, especially in diabetic patients with poor glycemic control, advanced age, long-term hormone use, and immunosuppressed patients, colonized resistant bacteria are likely to develop into pathogenic bacteria and become responsible for the next occurrence of infectious disease. For themselves, it will increase the difficulty of treatment and medical costs, and for others it will increase the risk of spreading drug-resistant bacteria.