Purity: Change in Istiḥāḍah Intensity Before Prayer

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 418:

If before prayers the slight istiḥāḍah of a woman becomes medium or excessive, she must do the things required of a woman with medium or excessive istiḥāḍah, which were mentioned earlier. If the medium istiḥāḍah of a woman becomes excessive, she must do the things required of a woman with excessive istiḥāḍah; and in the event that she has performed ghusl for medium istiḥāḍah, it is of no use and she must perform ghusl again for excessive istiḥāḍah.

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