Hi, Susten 100 mg contains progesterone, a female sex hormone that is used in the treatment of menstrual and pregnancy related hormonal problems. It is used as a part of hormonal replacement therapy to prevent hyperplasia of endometrium. As it contains progesterone which helps to regulate ovulation and menstruation, so Susten 100 mg is used in females infertility as well as increase the chance of getting pregnant. It is also used to relieve menopausal symptoms like hot flashes, flushed skin, night sweats, depression, mood changes, dryness of vagina, changes in sexual desire etc. You should take this medication with meal. You should keep taking this medication continuously as long as your prescribing doctor has advised to do so. Don t stop taking this medication without consulting your doctor first. If you notice any side effects from this medication like nausea, vomiting, abdominal pain, breast tenderness and enlargement, acnes, fatigue, changes in body weight, headache, allergic reactions etc and those side effects for long, then you should inform your doctor promptly for medical help. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician