Contraceptive pills and diet pills should not be taken together. Because the composition of the diet pill is not clear, it may affect the absorption of the pill or reduce the effectiveness of the pill, reducing the effectiveness of contraception in clinical practice, so the two can not be taken together. First of all, if you take the short-acting contraceptive pill, it is best to start taking it orally on the fifth day of your period, once a day, one pill at a time, and then stop taking it after 21 consecutive days. It is recommended that when you take the pill orally every day, it is best to take it at a fixed time so that the contraceptive effect will be better. Secondly, if you are taking the emergency contraceptive pill, you need to take it orally within 72 hours after intercourse. In addition, after stopping the pill there is often withdrawal bleeding, do not be nervous, mainly caused by the side effects of the pill.