First of all, we should choose the right time and method to apply for vacation according to our actual situation. If you can predict your physiological period in advance, it is best to explain the situation to the leader one or two days in advance to avoid the trouble caused by temporary leave. If it is sudden dysmenorrhea, it is best to inform the leader in time before going to work or just when going to work, and don't wait until the work is busy or urgent to say that you want to ask for leave.
According to the other person's gender and personality, choose the appropriate wording and tone to express the reason for leaving. If the other person is a female leader, you can directly say that you are unwell or have menstrual cramps. Most women can understand and sympathize with this situation. If the other person is a male leader, you can put it mildly, such as being unwell, having female problems and needing to see a doctor. Avoid being too straightforward or detailed.