How long does abnormal vaginal bleeding (Istihadah) in women last, and when does prayer become obligatory again after it?

Istihadah (metrorrhagia/non-menstrual bleeding) differs from hayd (menstruation) in reality and ruling. Istihadah is not limited by a duration, whereas the maximum duration for hayd is fifteen days. If bleeding continues after that, it is istihadah. A woman experiencing istihadah is considered pure, and she must pray and fast, and it is permissible for her husband to have intercourse with her. She must perform ablution for every prayer.