Mifepristone is the main drug currently used to terminate early pregnancy, and its use should be strictly controlled for indications and contraindications, and a comprehensive understanding of the side effects of the drug should be obtained. The main side effects of mifepristone include the following: i. Vaginal bleeding: the most important adverse effect of mifepristone is the prolongation of vaginal bleeding and, in a few cases, it can cause massive uterine bleeding [1]. The main causes of bleeding caused by mifepristone termination of pregnancy are incomplete abortion, residual villi and meconium, followed by endocrine disorders caused by mifepristone, with unsynchronized levels of estrogen and progesterone, which affect the repair of the endometrium and cause long-term bleeding. When such side effects occur, patients should visit a hospital promptly to identify the cause and treat the symptoms. II. menstrual changes: the main adverse effect of mifepristone for emergency contraception is menstrual changes, with early onset of menstruation in 12%-14% of patients and delayed menstruation in 25%-28% of patients, and the mean duration of delayed menstruation in patients in the 50 mg group (11 d) was significantly longer than in the 10 mg group (8 d) [2]. III. Allergic reactions: individual women may develop a rash, which manifests as itchy skin, and usually the degree of allergic reaction is mild, and the symptoms can be relieved more quickly after discontinuation of mifepristone or anti-allergic treatment. Allergic patients can cause severe allergic reactions, such as pallor, cold sweats, decreased blood pressure, and even shock [3]. Use with caution in allergic individuals. Fourth, gastrointestinal reactions: some early pregnant women have mild nausea, vomiting, abdominal pain and diarrhea after taking the drug, which are usually tolerated without special treatment and can be treated symptomatically if necessary. Adverse reactions of mifepristone can also be seen as dizziness, weakness, lower abdominal pain and anal cramping. In conclusion, the use of mifepristone should be strictly under the guidance of a physician or pharmacist in order to reduce and cope with the occurrence of adverse reactions.