Taking birth control pills can prevent pregnancy. There are different types of birth control pills, which can be broadly categorized into long-acting contraceptives, emergency contraceptives, and short-acting contraceptives. Long-acting contraceptive pills and short-acting contraceptive pills can be used as a regular form of contraception under the guidance of a doctor. However, emergency contraceptive pills should not be used regularly and can only be used as a remedy. Long-term use of emergency contraceptive pills may lead to menstrual disorders. Long-acting contraceptive pills can be taken on the fifth day after the onset of menstruation with one tablet, and another tablet on the twentieth day. Short-acting contraceptive pills are mainly taken on the fifth day after the onset of menstruation with one tablet per day for 22 days. Contraceptive pills are hormonal preparations and may have adverse reactions such as nausea, vomiting and abnormal menstruation, and long-term use may cause liver function damage. It is contraindicated for women suffering from breast cancer, cancer of the reproductive organs, abnormal liver function, thrombosis disease and so on. The specific use of contraceptives should be under the guidance of a doctor.