Contraceptives taken before intercourse are mainly oral contraceptives, and the main adverse reactions are early pregnancy-like reactions, such as nausea, vomiting, weakness, fatigue, dizziness and so on. Irregular vaginal bleeding, mainly seen in the lack of regular use of contraceptives and the possibility of missed doses, most do not need special treatment, but if the bleeding is large enough, timely intervention is needed. Weight change is mainly due to hormonal changes in the body, which leads to the possibility of obesity, need to strengthen exercise to avoid obesity. Some women will also have facial skin pigmentation, usually after stopping the drug symptoms can be gradually relieved, some women symptoms can not be relieved. Oral contraceptives need to pay attention to the regularity of taking, according to the amount of taking.