There are many causes of amenorrhea: 1. whether the recent medication, because of drugs that cause amenorrhea, such as taking contraceptives, antipsychotics, anti-thyroid drugs may cause the delay of menstruation. 2. whether the recent mental stress, excessive weight loss or excessive load exercise, can cause the delay of menstruation. 3. whether the recent operation of the uterine cavity, which leads to uterine adhesions, cervical canal adhesions, or even endometrial damage leading to amenorrhea. 4. If you have recently undergone an operation of the uterine cavity, resulting in adhesions of the uterine cavity, cervical canal adhesions, or even damage to the endometrium, this may cause amenorrhea. 4. If you have recently developed significant obesity, hirsutism, or facial acne, you should consider pathological causes of amenorrhea. A common clinical condition is polycystic ovary syndrome, which may also cause delayed menstruation.5. Premature ovarian failure may also cause delayed menstruation. Therefore, for delayed menstruation without pregnancy, it is generally recommended to go to the hospital for examination to understand the reason for the absence of menstruation before treating it symptomatically.