Purity: Transition to Slight Istiḥāḍah

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 423:

If the excessive istiḥāḍah of a woman becomes slight, she must do the things required of a woman with excessive istiḥāḍah for the first prayer; and for subsequent prayers, she must do the things required of a woman with slight istiḥāḍah. Furthermore, if medium istiḥāḍah becomes slight, a mustaḥāḍah must do the things required of a woman with medium istiḥāḍah for the first prayer, if she has not done so already.

-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)