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

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The Niddah Status

Only uterine bleeding can make a woman niddah. Though the most common cause of niddah is menstruation, niddah and menstruation are not synonymous.

The Onset of the Niddah Status

According to Torah law, bleeding only makes a woman niddah when it is uterine, one of a specific set of colors, and accompanied by an internal physical sensation called a hargashah. Rabbinic law expands these definitions, as we’ll see below.

Bleeding from a cut, wound, or abrasion (dam makkah), does not make a woman niddah.

Though the most common cause of niddah is menstruation, niddah and menstruation are not synonymous. Dam niddah (niddah bleeding) typically comes from shedding of the uterine lining, which can occur either with menstruation or as a result of hormonal fluctuations. This may happen at any point in the cycle, and can include bleeding induced by medications, such as withdrawal bleeding from hormonal contraceptives.


Torah law recognizes only four specific shades of red and the color black as niddah colors. But the expertise required to distinguish between different shades of red was lost in Talmudic times, and today any shade of red or black, including shades of brown that tend towards them, is considered a niddah color. Pink and peach are also considered shades of red.

Discharge that has no trace of red (e.g., clear, white, beige, yellow, or green) does not make a woman niddah. Brown the shade of coffee with milk or lighter, without any hint of red, also does not make a woman niddah.

Questionable colors are best checked in natural sunlight (holding the cloth or stained item in the shade rather than in direct sunlight), as colors may appear different in artificial lighting.

Darker shades of brown, or browns with a reddish tint, should be evaluated by a halachic authority. We also recommend having colors that seem to have a slight reddish tint–such as light shades of pink or peach–evaluated, since they can be difficult to assess.

Hargashah and Stains

Torah law only considers a woman niddah if she has an internal sensation defined as a hargashah accompanying her bleeding. Rabbinic law, however, sometimes considers a woman niddah even when she doesn’t have a hargashah.

If a woman has a bloodflow or sees blood exit her body, we presume that she had a hargashah, and she becomes niddah. If a woman discovers an apparent bloodstain on her clothing or another surface without a hargashah, then she may become niddah, depending on several halachic factors included in the laws of stains (see here).


If a woman is unsure of her status, as when she has bleeding with a questionable source or finds a bloodstain with a questionable color, she should not independently assume that she is niddah. Rather, she should consult a halachic authority. Until her status has been clarified, however, she should follow all the laws of niddah.

Uterine opening

Significant dilation of the uterus with an instrument can make a woman niddah even if no bleeding is detected. This is based on a halachic presumption that the dilation triggers niddah bleeding (“ein petichat hamakor b’lo dam”).

Halachic authorities debate what amount of dilation is needed for this halachic presumption to apply (opinions range from 4 to 20 mm). We follow the opinion that a dilation of 19 mm or more renders a woman niddah. Most routine gynecological procedures do not involve this degree of dilation.

Torah Sources

The laws of niddah appear in the Torah twice. Leviticus 15:19 states: “A woman who has a flow of blood in her body shall be a “niddah” for seven days, and all who touch her shall be ritually impure until sundown.” Leviticus 18:19 states: “A woman in the ritually impure state of niddah, you shall not approach for sexual relations.”

The first verse refers to the laws of ritual impurity (tumah v’taharah), most of which are no longer applicable today. The second verse, however, appears in the list of the most severely forbidden sexual relationships, such as adultery and incest, which remain fully relevant to this day.

The Torah categorizes a menstrual-type flow outside the usual time period or for longer than seven days as zavah (Leviticus 15:25). Since Talmudic times, Halacha has made no practical distinctions between niddah and zavah. In common usage, including on this website, the term niddah refers to either status.

This page was updated on 25 May, 2024.

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All health and health-related information contained within Nishmat's Women's Health & Halacha Web site is intended to be general in nature and should not be used as a substitute for consulting with your health care professional. The advice is intended to offer a basis for individuals to discuss their medical condition with their health care provider but not individual advice. Although every effort is made to ensure that the material within Nishmat's Women's Health & Halacha Web site is accurate and timely, it is provided for the convenience of the Web site user but should not be considered official. Advice for actual medical practice should be obtained from a licensed health care professional.

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