Birth control pills are usually taken one pill at a time and can be taken up according to the instructions. Contraceptives are categorized into short-acting pills, long-acting pills, and emergency pills. Short-acting pills are usually taken one at a time and are used in cycles of 21 days each. Long-acting pills are usually used once a month and only one pill is needed each time. Emergency contraceptive pills are taken within seventy-two hours of unprotected sex or contraceptive failure, also one pill at a time. Contraceptives are mainly metabolized through the liver and kidneys, which tends to affect women’s endocrine function, while some patients may experience adverse reactions such as nausea, vomiting and dizziness. Any contraceptive pill needs to be taken reasonably under the guidance of a professional doctor, remember not to take the pill privately to avoid adverse reactions.