Dear Ma'am, Progestrogens are common hormones given to delay or cause withdrawal bleeding in women with an irregular menstrual cycle. Side effects of regesterone include: Nausea, vomiting, breast tenderness,  mood swings. Irregularity in the next cycle.( Early or delayed) However,  these effects are temporary and patient becomes better once the medication is stopped. I hope I was able to resolve your concerns. Regards, Dr. Aditi Kishore Shinde