Side effects can vary depending on the type of antibiotic. Most of the antibiotics may have allergic reactions, and may also cause ototoxicity, nephrotoxicity, neurological and other toxic reactions, while large doses or long-term application of antibiotics may easily lead to secondary infections. According to the different chemical structures, antibiotics can be categorized into quinolone antibiotics, β-lactam antibiotics, macrolides, aminoglycoside antibiotics and so on. 1. Allergic reaction: β-lactam antibiotics such as penicillin and cephalosporin are more common. The reason of allergic reaction is related to the patient’s individual physique and the drug itself, specifically manifested as rash, itching, cough, wheezing, dyspnea, and even anaphylactic shock. 2. Toxic reactions: often related to the dose of the drug, too long, mainly including neurotoxicity, ototoxicity, nephrotoxicity, etc., as well as gastrointestinal toxicity, cardiac toxicity, etc., which can lead to gastrointestinal reactions, cardiac arrhythmia and so on. 3. Dual infections: High-dose or long-term application of antibiotics, especially broad-spectrum antibiotics, can cause dysregulation of the normal flora in the body, resulting in dual infections, such as oral mycobacterial infections, Candida albicans vaginitis and so on. The use of antibiotics needs to be based on the type of pathogenic bacteria, the antibacterial spectrum of the drug by the doctor to choose the appropriate sensitive drugs for treatment, the patient should be full dose, full course of medication to avoid serious side effects, the use of medication during the discomfort, it is recommended to consult a doctor in a timely manner, do not delay, so as not to cause adverse consequences.