Tetracyclines include tetracycline, doxycycline, tigecycline, etc. It is important to note that adverse reactions such as nausea and vomiting may occur with the use of tetracyclines. Tetracyclines are divided into three generations. The first generation of tetracyclines include tetracycline, hyoscine, and chlortetracycline; the second generation of tetracyclines include doxycycline, metacycline, and minocycline; and the third generation of tetracyclines include tigecycline. After taking tetracycline, patients may experience adverse reactions such as nausea, vomiting, epigastric discomfort, abdominal distension, and diarrhea. In addition, hemolytic anemia, thrombocytopenia, neutropenia, benign intracranial pressure increase and other adverse reactions may occur, occasionally pancreatitis, esophagitis, esophageal ulcers and other adverse reactions, patients with fatty liver degeneration and women in pregnancy may develop hepatotoxicity after using the drug, and patients with pre-existing significant renal impairment may experience aggravation of azotemia, hyperphosphatemia and acidosis. Women in the middle and late stages of pregnancy, infants and children under 8 years of age may experience yellowing of the teeth, enamel hypoplasia, and bone growth inhibition when taking this drug. If you need to take this drug, do so under the supervision of a physician.