Liver function transaminases are elevated after taking doxycycline for three days, and usually will gradually return to normal after stopping the drug. Elevated liver aminotransferase on doxycycline is an adverse drug reaction, mainly because the drug is partially metabolized in the liver, which can lead to abnormalities in liver function. If the aminotransferase is only mildly elevated at present, it will return to normal on its own after the condition is under control and the drug is stopped. However, if the liver transaminases are seriously elevated, the drug should be stopped immediately, and liver-protecting drugs, such as compound glycyrrhizin and reduced glutathione, should be taken orally at the same time. Liver transaminases are elevated on the third day of taking doxycycline, cooperate with the doctor to take treatment or therapy.