The first reference to menstruation in the Bible, and likely the earliest historically, occurs in Genesis 31, which is part of the “J” (Jahwist) source of the Pentateuch. Jacob, having worked as a shepherd for his father-in-law, Laban, for fourteen years, absconds in the night with his wives and servants. Unbeknownst to Jacob, his wife Rachel has taken Laban’s terafim (probably household gods). Laban searches for the terafim, finally coming to Rachel’s tent. Rachel, meanwhile, has placed the terafim in a camel cushion and is sitting on them. When her father enters the tent, she says, “Let my father not be angry that I do not rise for him, for the way of women is upon me” (v. 35).

Rachel is presumably lying, but for the lie to be credible, it would have to reflect common practice around the time that the text was written. Perhaps Rachel would not have wanted her father to see her blood, or perhaps she would have been concerned about making a mess. In any case, the text does not reflect any particular taboo on menstruation. Rachel’s matter-of-fact description of her period as “the way of women” makes no reference to ideas of impurity found elsewhere in the Bible.

In contrast to this early narrative, most references to menstruation in the Bible portray it as a source of impurity (Ritual impuritytum’ah). Leviticus 15, which belongs to the “P” (Priestly) source, deals with menstruation within the broader context of genital discharges. The text divides roughly into two sections: verses 2–18 deal with male discharges, and verses 19–30 deal with female discharges. Each of these sections is further subdivided into what might be described as “normal” and “abnormal” discharges. The text has a chiastic (AB:BA) structure: abnormal male discharges come first (vv. 2–15), followed by normal male discharges (vv. 16–18), then normal female discharges (vv. 19–24), and finally, abnormal female discharges (vv. 25–30).

For a man, the “normal” discharge is ejaculation, whether within or outside intercourse, which causes impurity until evening. “Abnormal” discharges include “flows” or “blockages,” presumably due to infection or disease. Such discharges cause impurity as long as they last and for an additional seven days after they cease, at the end of which the man must present two birds as offerings.

For a woman, the “normal” discharge is regular menstruation, which causes impurity for seven days from the onset of bleeding (v. 19). An “abnormal” discharge is an off-cycle flow of blood that lasts for “many days” (v. 25). Like an abnormal male discharge, this causes impurity for the duration of the condition and for an additional seven days, after which the woman must present two birds as offerings.

Although the structure of the text suggests a deliberate parallel between ejaculation and menstruation, they inevitably cause impurity for different lengths of time. A one-day impurity for menstruation would not make sense, since a typical period lasts close to a week, while a seven-day impurity for every ejaculation would be onerous. In other respects, the male and female discharges are treated as essentially the same. Both the discharges themselves and people who have them transmit impurity to other people, to clothing, and to certain objects through physical contact.

The primary consequence of impurity, as far as the Priestly source is concerned, is that it contaminates the tabernacle (v.  31). A person need not necessarily avoid becoming impure (which is often impossible) but must take care to avoid approaching the tabernacle and having contact with sacred objects until the impurity has passed.

Leviticus 15 prescribes washing in water after various types of direct or indirect contact with genital discharges. Washing is required after ejaculation or sexual intercourse (vv. 16, 18), and a man who recovers from an abnormal discharge is required to “wash his flesh in living water” (v. 13). (As elsewhere in the chapter, “flesh” here probably means “penis.”) Washing is also required after touching the “flesh” of a man with an abnormal discharge (v. 7), after contact with his spittle (v. 8) or unwashed hands (v. 11), and after contact with anything he has sat or lain down on (vv. 4–6). The same rules apply to contact with the bed or vessel of a menstruating woman or a woman with abnormal bleeding (vv. 21–22). However, there is no explicit requirement for the woman herself to wash, though some scholars believe it is assumed.  

One possible piece of evidence for washing after menstruation comes from the case of Bathsheba, whom David sees bathing on a rooftop (2 Sam 11:2). Bathsheba would most likely have been taking a “jug bath,” pouring rainwater collected on the rooftop over herself with a jug. David summons her to his palace and sleeps with her, after which the text notes that “she was purifying herself/becoming purified (mitkaddeshet) from her impurity” (v. 4). This has led many readers to the understanding that Bathsheba was bathing to purify herself after menstruation. However, purification is not mentioned in connection with the bath but two verses later, after David and Bathsheba have sex. If mitkaddeshet is taken as passive rather than reflexive (either is grammatically possible), it may simply mean that Bathsheba was emerging from her state of impurity when David slept with her. It is also possible that verse 4 does not refer to impurity from menstruation at all but from sexual intercourse.

Whether or not the Bible reflects a practice of washing after menstruation, there is no evidence for the practice of immersing completely in a Ritual bathmikveh, or freshwater bath, which seems to have emerged later in the Second Temple period.

Leviticus 15 presents sex during menstruation as one of the many ways in which ritual impurity can be communicated from one person to another. Verse 24 states: “And if a man lies with her, her impurity is communicated to him; he shall be impure seven days, and any bedding on which he lies shall become impure.” Just as sexual intercourse communicates the “male” impurity of semen to the female partner (v. 18), sex during menstruation communicates the “female” impurity of menstruation to the male partner, and he remains impure for the same length of time as a menstruating woman. There is no hint that such relations are prohibited.

In contrast, Leviticus 18:19 and 20:18 condemn sex with a menstruating woman in the strongest terms. These verses occur in passages dealing with prohibited sexual relations and belong to the Holiness legislation (H), a component of the Priestly source that deals more with the general comportment of the Israelite population than with the strictly ritual and cultic matters that concern the remainder of P.

Leviticus 18:19 phrases the prohibition using the language of ritual impurity: “Do not come near a woman during her period of impurity to uncover her nakedness.” The conclusion of the passage emphasizes the severity of violating the sexual prohibitions, again using the language of impurity: “Do not defile yourselves [or: ‘make yourselves impure’] in any of those ways, for it is by such that the nations that I am casting out before you defiled themselves. Thus the land became defiled; and I called it to account for its iniquity, and the land spewed out its inhabitants” (vv. 24–25). In Leviticus 20:18, the purity language is absent, but the condemnation is similar: “If a man lies with a woman in her infirmity and uncovers her nakedness, he has laid bare her flow and she has exposed her blood flow; both of them shall be cut off from among their people.”

H’s divergence from the remainder of P here in part reflects its concern for the holiness and purity of the Israelite people as opposed to the holiness and purity of the sanctuary. It may also suggest an understanding of menstruation as posing a threat to the essential purity of the male body that distinguishes it from other types of merely ritual contaminants.

The prohibition of sex with a menstruating woman is referenced several times in Ezekiel, a prophetic book that is closely related to P and especially to H. In a passage contrasting righteous and wicked men, Ezekiel states that a righteous man, among other attributes, “does not approach a menstruating woman” (Ezek 18:6). Similarly, a passage describing the wickedness of the inhabitants of Jerusalem accuses them of having with sex menstruating women (22:10). Ezekiel’s repeated classification of this particular transgression as a paradigmatic sin—alongside murder, theft, and oppression of the poor—is striking. In chapter 18, it is the only sexual transgression mentioned besides adultery.

In the Prophets and Writings, the people of Israel, the land of Israel, or the city of Jerusalem is sometimes likened to a menstruating woman.

One such case is Ezekiel 36:17: “O mortal, when the House of Israel dwelt [literally, ‘sat’] on their own soil, they defiled it with their ways and their deeds; their ways were in my sight like the impurity of a menstruous woman [niddah].” Ezekiel, more than any other book of the Bible, associates sin with impurity. In this verse, menstrual impurity is regarded as so severe that it is used to emphasize the gravity of Israel’s sin. The image of menstrual impurity transferring to the surface on which the menstruant sits reflects the idea that sins contaminate the land, a notion also found in Leviticus 18 (see above).

The idea that sin contaminates the land is also found in Ezra 9, a late biblical text that is heavily dependent on Leviticus 18. Ezra describes the land of Judah as a “niddah-land,” which has been contaminated by the niddah of the peoples who occupied it during the Babylonian exile (v. 11). Here, the term niddah, which usually refers to menstrual impurity, takes the place of tum’ah, “impurity,” in Leviticus 18. This change of terminology may be intended to compare sinful people to a menstruating woman whose impurity is transferred to the land. However, the term niddah is sometimes used for impurity in general rather than menstrual impurity specifically, especially in late biblical texts, so it is possible that no such overtones are intended.

In the first chapter of the book of Lamentations, the destroyed city of Jerusalem is likened to a niddah:

Jerusalem has greatly sinned,

Therefore she is become a niddah.

All who admired her despise her,

For they have seen her nakedness;

And she can only sigh

And shrink back. 

Her impurity [tum’atah] clings to her skirts.

She gave no thought to her future;

She has sunk appallingly,

With none to comfort her.

— See, O LORD, my misery; How the enemy jeers! (Lam 1:8–9)

A few verses later, the image recurs:

Zion stretches out her hands,

but there is no one to comfort her;

the LORD has commanded against Jacob

that his neighbors should become his foes;

Jerusalem has become

a niddah among them. (Lam 1:17)

The image here seems to be that of a menstruating woman whose blood is visible in her skirts. The impurity of menstruation functions as a metaphor for Jerusalem’s sin, while the exposure of blood symbolizes the city’s disgrace. Here as well, however, it is not impossible that niddah refers to impurity generally and not to menstruation in particular. Modern translations, including JPS, interpret it in this more generic sense.

Although most of the biblical texts on menstruation describe it as a source of impurity, they reflect different attitudes toward it. In Leviticus 15 (P), menstruation is one source of ritual impurity among many, no more severe than male ejaculation, while in Leviticus 18 and 20 (H), it is the subject of a sexual prohibition, arguably reflecting the idea that menstrual blood threatens the purity of the male body.  In Ezekiel and possibly Lamentations and Ezra, the impurity of menstruation seems even more severe and symbolizes grave sin.

Whether this represents a chronological trajectory depends on the relative times at which the texts were composed, which is a subject of debate. Although there is a consensus that J (in which the story of Rachel and the terafim appears) is among the earliest sources in the Bible and that Ezra 9 is among the latest, there is disagreement over the chronological relationship among P, H, and Ezekiel. (Lamentations and Ezekiel are probably roughly contemporaneous.) There is a strong argument that H is later than P and that Ezekiel is later than both, suggesting that menstruation was increasingly problematized over time. But it is also possible for multiple attitudes toward menstruation to have existed simultaneously. The different genres of the texts may also account for some of their differences. While a legal text like Leviticus 15 treats menstrual impurity from a technical perspective, popular attitudes may at times have been more along the lines of Ezekiel or Lamentations.