How can a woman afflicted with an illness, for which medication causes her continuous bleeding, perform the acts of worship of prayer and fasting?

If a woman afflicted with istihada (prolonged vaginal bleeding outside of menstruation) had a previous monthly habit, she should act according to that habit. She should refrain from prayer, fasting, and intercourse during the days of her previous habit, then perform ghusl (ritual bath) and resume her normal practices. This is what is indicated by the hadiths of Umm Habiba, Fatimah bint Abi Hubaysh, and Umm Salamah.