Eating emergency contraceptive pills can be contraindicated for three days, but no absolute contraindication requirements, the purpose is mainly to reduce the contraceptive pill to take and nausea, vomiting and other reactions, which in turn reduces the absorption of the drug, thereby affecting the effectiveness of contraception. However, taking emergency contraceptive pills should pay more attention to the time of taking, appropriate fasting before and after taking, avoid taking too many times and other precautions, need to pay attention to the relevant taboos, so as not to affect the effect of taking. The main reason emergency contraceptive pills are mainly composed of highly effective progesterone, it is difficult for the human body to directly affect the level of progesterone through the digestion and absorption of food, diet and progesterone effect is not very relevant, so there is no need to be overly concerned about the type of food. The use of 1, taking time: emergency contraceptive pills usually have to be taken within 72 hours of unprotected sex, the sooner you take the contraceptive success rate is higher. If more than 72 hours to take, there is a greater chance of contraceptive failure; 2, appropriate fasting: 2 hours before and after taking emergency contraceptive pills should try to prohibit food and water. The purpose is to reduce the stimulation of the contraceptive pill on the gastrointestinal tract, to avoid the emergence of vomiting, stomach pain and other adverse reactions; 3, to avoid excessive use: emergency contraceptive pills on women’s side effects, too much easy to lead to endocrine disorders, menstrual disorders, and in serious cases will cause uterine fibroids and other diseases. 1 year should not be more than the number of times to take emergency contraceptive pills 4 times. The emergency contraceptive pill should not be used as a regular means of contraception. If you do not take short-acting or long-acting contraceptive pills, it is recommended that you use a condom as much as possible when having unanticipated sexual intercourse to avoid harming your body.