Hi, Thanks for posting your query. I am happy to address your questions. Susten is progesterone tablet. Its responsible for getting periods on time. So I assume your doctor wants to induce it which is why she is asking you to take it orally. Once you stop it you will get your periods within a week. Susten can also be used in case you need it for providing additional progesterone to help sustain pregnancy after cycles. Yes, it will induce the menstruation and will be associated with abdominal and back pains. Hope I have answered your query. If you have any further questions, I will be happy to help. Thanks