The World Federation One Stop Fiqh

Ruling 416

Based on the opinion held by most jurists (mashhūr), the fast of a woman who has excessive istiḥāḍah is valid if she performs ghusl for maghrib and ʿishāʾ prayers the night before the day she wants to fast and if she performs the ghusls that are obligatory for the prayers of the day. However, it is not farfetched to consider the validity of her fast as not being conditional on her performing ghusl, just as it is not conditional – based on a stronger opinion (aqwā)43 – for a woman who has medium iistiḥāḍah.44

43 For practical purposes, where an opinion is stated to be ‘stronger’, a fatwa is being given.
44 This rule is clearly stated in Ruling 1613.