How long a pill lasts is related to its type. Long-acting contraceptives, short-acting contraceptives, and emergency contraceptives all last different amounts of time. 1. Combined long-acting contraceptive pills are formed by long-acting estrogen and progestin, and one pill can last up to one month. 2. Oral contraceptives are divided into short-acting and emergency contraceptives. Short-acting contraceptive pills a can not achieve contraceptive effect, need to be taken regularly, the first menstrual day to take the first, for 21 days, can ensure that this month’s menstrual cycle has a contraceptive effect. 3. Emergency contraceptive pills are taken orally within 72 hours after unprotected sex, with an additional pill 12 hours later, the contraceptive rate can be up to 90%, but if you only take it once, the failure rate will be higher. Emergency contraceptive pills are only effective for 72 hours before taking the pill. If you need to use birth control pills, please consult your physician and follow the doctor’s instructions.