Does megestrol acetate always stop heavy bleeding? i've been taking it for a week and it slowed my bleeding down but tonight i started bleedi again.

Not always: Megestrol acetate is a hormone that may decrease or eliminate heavy bleeding from the uterus. It is used after other causes of bleeding (cancer, precancer, polyps, uterine lining overgrowth, etc) has been ruled out. Menstrual period suppression can be difficult. Doses of suppression hormones may need to be adjusted to avoid break through bleeding.