Hi, Thanks for posting in HCM. I understand your concern. Prometrium contains progesterone, which is a female hormone. Progesterone is used as part of combination hormone replacement therapy with estrogens to reduce menopause symptoms and to reduce the risk of cancer of the uterus. Side Effects which can occur due to this medication include: Nausea, bloating, breast tenderness, headache, change in vaginal discharge, mood swings, blurred vision and dizziness. If any of these effects persist or become worse, you need to seek medical attention promptly. Hope the information provided would be helpful. All the best.