Nisaa
No, but it does mean stepping out of the mosque right away, because presence in the mosque is what i'tikaf actually is, not just where it happens to take place. Whether you have to restart it later depends on how you observed it and which school you follow.
I'tikaf is dwelling inside a mosque with the intention of devotion, and the Qur'an names the mosque as the setting itself: [Al-Baqarah 2:187] describes a husband and wife “while you are staying for worship in the mosques” (wa antum 'akifuna fi al-masajid). Being physically present in the mosque, not merely intending devotion, is what the word describes.
That is exactly the condition hayd removes. The same evidence that keeps a menstruating woman out of the mosque generally, [An-Nisa' 4:43] read alongside the hadith of Umm 'Atiyyah (see can a menstruating woman enter or stay in a mosque), applies here without any extra step, since i'tikaf has no existence outside the mosque to retreat to. 'Aishah (Radi'Allahu Anha) narrated: “The Messenger of Allah (Salla Allahu 'Alayhi Wa Sallam) would bring his head close to me from inside the mosque while he was in i'tikaf, and I would comb it, while I was menstruating.” (Narrated by al-Bukhari). She stayed in her room next to the mosque and reached only as far as his head; she did not go in to comb it while she was bleeding. If that is what her own hayd asked of her toward her husband's i'tikaf, it asks the same of a woman doing i'tikaf herself: leave, and do not return until you are pure.
Once she is out, what she owes for the interrupted time is where the schools genuinely differ, because they disagree on whether a voluntary act of worship, once begun, has to be completed or made up.
- Hanafi: beginning a voluntary act binds you to finish it, the same principle that governs a nafl fast broken partway through. Once purity returns, she makes up the days her period cost her.
- Shafi'i and Hanbali: voluntary i'tikaf is not binding to complete once begun. If she had not vowed a fixed number of days, she is not obligated to make up what her period interrupted, though doing so is praiseworthy. A specific vow (nadhr) is different: what was vowed must still be fulfilled once she is pure.
- Maliki: continuity is itself a condition of a valid i'tikaf. A woman who stipulated at the outset, before entering the mosque, that illness or menstruation would not break her i'tikaf may resume the same session where she left off once pure. Without that stipulation, hayd breaks the continuity outright: a vowed i'tikaf must be started over from the beginning, and a voluntary one simply ends.
In practice, most women planning an extended stay, especially the last ten nights of Ramadan, stipulate this in advance for exactly this reason: it costs nothing to say at the outset, and it settles the Maliki concern before it arises.
None of this touches what still reaches her outside the mosque. Dhikr, du'a, istighfar and charity remain fully open; see what worship stays open during hayd. If her i'tikaf falls inside Ramadan, her fast is a separate question entirely, governed by its own rule rather than this one. Istihadah does not raise any of this in the first place: a Companion of the Prophet remained inside the mosque for i'tikaf while she had istihadah; see can a woman with istihadah enter or stay in a mosque. Ordinary travel away from the mosque raises a different question again, about Ghusl rather than about staying inside; see what if your period starts while you're travelling for how tayammum fits in there.