The oral contraceptive pill (hereinafter referred to as the pill) was developed in the 1950s and gradually came into widespread use in the 1960s. Under normal use, the contraceptive rate is as high as 99%, making it a very effective method of contraception. It is not only used to prevent pregnancy, but is also often used to regulate irregular periods, reduce menstrual pain, treat premenstrual syndrome, endometriosis, or acne. The main ingredients of the pill are the female hormones (estrogen) and progesterone (progesterone). In terms of ingredients, they can be divided into those that have both hormones (compounded oral contraceptives) and those that have only progesterone and no estrogen. The pill can prevent pregnancy simply because it inhibits ovulation, makes the endometrium thinner, and thickens the cervical mucosa so that spermatozoa cannot enter the uterus. The result is that spermatozoa cannot easily enter the uterus, and even if they do, they cannot find an egg, and even if they do, the intrauterine environment does not allow them to stay for a long time. The most common side effects of birth control pills include nausea or vomiting, breast swelling, irregular periods (breakthrough bleeding), decreased sex drive, headaches, and emotional instability. The majority of these side effects, if they occur, are not serious and will improve within 2 to 3 months with continued use of the drug. Therefore, we often tell our patients to be patient and observe the pill for a few weeks if they are uncomfortable at first, and they usually get better after a while.