סימן קכב סעיף יב

אֵין רוֹחֲצִין בְּתִשְׁעָה יָמִים אֵלּוּ אֲפִלּוּ בְּצוֹנֵן. אַךְ לִרְפוּאָה, כְּגוֹן יוֹלֶדֶת אוֹ מְעֻבֶּרֶת שֶׁקְּרוֹבָה לָלֶדֶת, שֶׁטּוֹב לָהּ לִרְחוֹץ, וְכֵן אָדָם חָלוּשׁ שֶׁצִּוָּה אוֹתוֹ הָרוֹפֵא לִרְחוֹץ, מֻתָּרִין לִרְחוֹץ אֲפִלּוּ בְּחַמִּין. וְכֵן נִדָּה, רוֹחֶצֶת וְטוֹבֶלֶת כְּדַרְכָּהּ. וְאִם טוֹבֶלֶת בַּלַּיְלָה שֶׁאַחַר תִּשְׁעָה בְּאָב וְאִי אֶפְשָׁר לָהּ לִרְחוֹץ אָז, יְכוֹלָה לִרְחוֹץ בְּעֶרֶב תִּשְׁעָה בְּאָב. וְכֵן כְּשֶׁלּוֹבֶשֶׁת לְבָנִים, יְכוֹלָה לִרְחוֹץ מְעַט כְּדַרְכָּהּ, כֵּיוָן שֶׁאֵינָהּ עוֹשָׂה לְתַעֲנוּג.

You should not take a bath²²Washing of the face, hands and feet is permitted. (Ibid. 551:94) during these nine days, even in cold water. However for medical reasons, as, for example, when a woman has given birth, or a pregnant woman, close to childbirth, for whom bathing is beneficial, or a weak person, whose physician ordered him to bathe,²³Only if he was ordered to bathe daily in hot water. (Shaar Hatzion 551:94) these are permitted to bathe, even in warm water.²⁴On Tishah beAv, itself, however, he should refrain from doing so. (Ibid.) A woman, who was menstrually unclean, may bathe and immerse herself in the mikveh as usual.²⁵Even with hot water. (see Biyur Halachah 551:16) If she has to immerse herself on the night after Tishah beAv, and it will be impossible for her to take the required bath (on Tishah beAv), she is permitted to bathe on erev Tishah beAv. Similarly, when she puts on clean undergarments, [to begin counting her seven clean days], she is permitted to bathe a little in her accustomed manner because she is not doing it for pleasure.

תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)