Nishmat's Women’s Health and HalachaIn memory of Chaya Mirel bat R' Avraham

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Onot after eleven-day cycle

28 April, 2014



I have a question regarding calculating onot. I became a niddah on the 10th of Nissan, counted 5 days, and then started the shiva nekiim. On day 6 of the shiva nekiim (day 11 of the menstrual cycle), I began what appeared to be another period, for a full 5 days.

My question is, do I need to keep the onot from the earlier cycle as well? I've never had a cycle so short that I didn't even get tahor, so I'm wondering if this affects calculating onot, or if the days are all uprooted by the new period?

Thank you:


The onah beinonit and the veset haflagah from the earlier period were uprooted and those scheduled onah dates need not be observed. However, the yom hachodesh from your earlier period was not uprooted by the newer period. It is only uprooted once the date passes and you have not begun bleeding. Therefore you should keep the yom hachodesh from the earlier period in addition to the onot calculated from the newer period. 

While you are not required to observe the previously scheduled yom haflagah, there is halachic debate whether that actual interval was uprooted by the newer, short interval. We advise calculating both the newer short interval, as well as the older longer interval from the date of your most recent period. This means that if your last haflagah was 28 days, and your new interval is 11 days, you should calculate 2 ymei haflagah from your most recent period – day 11 as well as day 28.

In sum, you should observe your previous yom hachodesh, the new onah beinonit, the new yom hachodesh, the new haflagah (11 days) and the old haflagah recalculated from the date of your later period.

Please feel free to get back to us with any further questions.


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