Due to individual differences, taking birth control pills are subject to different degrees of side effects, and it is not possible to achieve 100% contraception, the scope of application of each contraceptive pill varies. Therefore, there is no such thing as the safest and least harmful, but do not use emergency contraceptive pills as a routine. Contraceptive pills are categorized into three types: short-acting contraceptive pills, long-acting contraceptive pills and emergency contraceptive pills. Short-acting contraceptives contain low levels of estrogen and progesterone and are metabolized quickly, so side effects are relatively minor compared to other contraceptives. Long-acting contraceptive pills contain more hormones and therefore have a longer metabolism time and more adverse effects. The main ingredient of emergency contraceptive pills is high-efficiency progestin, and the hormone content is greater than the other two. Taking emergency contraceptive pills may cause side effects such as irregular menstruation, nausea, vomiting, dizziness, and fatigue. It is important to take the pill in a reasonable manner and according to the doctor’s instructions. If there is any physical abnormality during the use of the pill, you need to go to the hospital for examination.