What Is Istihaza? How Is It Calculated?
In the jurisprudence of menstruation, istihaza is bleeding that comes not from the uterus but from within the vagina. This bleeding may also be considered legal (ḥukmī).1,2,3,4 It is also referred to as corrupted or irregular blood (dam al-fāsid). Istihaza blood is the bleeding seen by a non-pregnant woman outside of her menstrual period.5
Types of Istihaza (Irregular Bleeding)
- Bleeding seen before the age of 9, or below the minimum age at which a girl can menstruate, is considered istihaza.
- For women who have reached menopause, bleeding other than red or black is considered menstrual blood. According to the preferred opinion, this age is 55.
- Bleeding seen by a pregnant woman is istihaza, that is, irregular bleeding.
- After 40 days have passed from the initial postpartum (nifas) bleeding of a woman who has given birth, any bleeding seen until her menstruation begins again is considered istihaza. You can read more about this topic in our article on postpartum bleeding.
- Bleeding that lasts less than the minimum duration of menstruation, which is 3 days and 3 nights, is considered istihaza.
- Of the bleeding that exceeds 10 days, the portion that goes beyond the days corresponding to her usual menstrual period is considered istihaza.
Now, let us explain in detail the issue that “of the bleeding exceeding 10 days, the portion beyond the days corresponding to the menstrual period is istihaza,”6,7,8,9,10
Istihaza (Irregular Bleeding) Exceeding the Menstrual Duration
Let us consider a woman whose habit is 5 days of bleeding and 25 days of purity. For ease of understanding, let us assume that she always begins her menstruation on the 1st day of the month. For this woman:
If Bleeding Extends After Her Menstrual Period
Case 1: If the Start Date of Menstruation Does Not Change
If after seeing 5 days of bleeding and 25 days of purity, she then sees bleeding from the 1st to the 12th day (inclusive) of the next month, the first 5 days, which are her habitual period, are considered menstruation, and the following 7 days are considered istihaza. Even if she had only seen blood on the 1st, 9th, and 12th, the ruling would not change. Because purity of less than 15 days is treated as continuous bleeding, she is considered to have bled continuously from the 1st to the 12th.
Note: If this woman had seen bleeding up to the 9th, that is, less than 10 days (240 hours), her menstruation would have shifted to 9 days. Or if she had seen bleeding up to the 4th, her menstruation would have shifted to 4 days. Since the bleeding exceeded 10 days, the ruling follows her last established habit.
Case 2: If the Start Date of Menstruation Is Delayed
If after seeing 5 days of bleeding and 25 days of purity, she then sees bleeding from the 3rd to the 14th day (inclusive) of the next month, only the last 3 days (3rd, 4th, 5th days) of her habitual 5-day period are considered menstruation, and the following 9 days are considered istihaza.
Even if she had only seen blood on the 3rd and the 14th, the ruling would not change. Because purity of less than 15 days is treated as continuous bleeding, she is considered to have bled continuously from the 3rd to the 14th.11,12,13,14
The reason why the menstruation does not shift fully to 5 days here is that there is no change in the habitual time window (mekān) of menstruation. As stated above, according to the rule that “of the bleeding exceeding 10 days, the portion beyond the habitual menstrual days is istihaza,” since the minimum qualifying amount (niṣāb), which is 3 days, is present within her habitual period, the habitual time window remains unchanged, and the non-overlapping parts are treated as istihaza. The prayers from the 5th onward, and any obligatory or necessary fasts, must be made up.
Case 3: If the Start Date of Menstruation Is Greatly Delayed
If after seeing 5 days of bleeding and 25 days of purity, she then sees bleeding from the 4th to the 15th day (inclusive) of the next month, since the minimum qualifying amount (3 days) does not occur within her habitual 5-day period, she is considered menstruating from the 4th to the 8th, and the bleeding from the 9th to the 15th is considered istihaza.
Here, unlike the previous example, the habitual time window has changed for that month because the minimum qualifying amount of bleeding did not occur within the original days (1st–5th). The prayers after the 8th, and any obligatory or necessary fasts, must be made up.
For subsequent months, her menstruation will again be calculated as the 1st to the 5th, because the bleeding exceeded 10 days and the habitual basis has not permanently shifted.
If Bleeding Begins Before Her Menstrual Period
Case 1: If the End Date of Menstruation Does Not Change
If after seeing 5 days of bleeding and 24 days of purity, she then sees bleeding from the 30th day until the 11th day (inclusive) of the next month, the first 5 days of the new month are menstruation, while the 30th day and the days from the 6th to the 11th are considered istihaza. Even if she had only seen blood on the 30th and the 11th, the ruling would not change, as purity of less than 15 days is treated as continuous bleeding.
Case 2: If the End Date of Menstruation Changes
If after seeing 5 days of bleeding and 17 days of purity, she then sees bleeding from the 23rd day until the 4th day (inclusive) of the next month, only the first 4 days (1st, 2nd, 3rd, 4th) are considered menstruation, and the preceding 8 days are considered istihaza. Even if she had only seen blood on the 23rd and the 4th, the ruling would not change.
The reason why the menstruation does not shift to 5 full days is that there is no change in the habitual time window. Since more than the minimum qualifying amount (3 days) occurred within the habitual period, the overlapping part remains menstruation and the rest is treated as istihaza. The prayers before the 1st, and any obligatory or necessary fasts, must be made up.
Case 3: If the End Date of Menstruation Changes Significantly
If after seeing 5 days of bleeding and 15 days of purity, she then sees bleeding from the 21st day until the 2nd day (inclusive) of the next month, since the minimum qualifying amount (3 days) does not occur within her habitual 5-day period, she is considered menstruating from the 21st to the 25th, and the bleeding from the 26th to the 15th is considered istihaza.
If in subsequent months the bleeding again exceeds 10 days, her menstruation will still be calculated as the 1st to the 5th, because the habitual basis has not changed.
1 Ahmet Mahmut ÜNLÜ, Faith and Islam Catechism (Istanbul: Tuana Publishing, 2015), 233
2 Ahmet Mahmut ÜNLÜ, Treatise on Women's States (Istanbul: Tuana Publishing, 2015), 8
3 Imam Birgivi, Special حالات for Women, trans. Hüsamettin VANLIOĞLU et al. (Istanbul: Ismailaga Publishing, 2024), 14
4 Imam Mevsili, Al-Ikhtiyar, trans. Hüsamettin VANLIOĞLU et al. (Istanbul: Ismailaga Publishing, 2022), 75
5 Imam Sarakhsi, Al-Mabsut, ed. Cevat AKŞİT, vol. 9 (Istanbul: Gümüşev Publishing, 2018), 231
6 ÜNLÜ, Faith and Islam Catechism, 238
7 ÜNLÜ, Treatise on Women's States, 17
8 Birgivi, Special حالات for Women, 39
9 Mevsili, Al-Ikhtiyar, 82
10 Sarakhsi, Al-Mabsut, 281
11 ÜNLÜ, Faith and Islam Catechism, 233
12 ÜNLÜ, Treatise on Women's States, 7
13 Birgivi, Special حالات for Women, 22
14 Sarakhsi, Al-Mabsut, 244
