Can one rinse the mouth out with mouthwash or water on a fast day? If I will be very careful not to swallow any of the liquid is there a problem? I am very uncomfortable if I am not able to rinse my mouth out in the morning. Is there any difference between yom kippur and other fasts on this question?


It is permitted to rinse one’s mouth with mouthwash, with the exception of Yom Kippur, when it is prohibited. The reason for this is that one is careful in any case not to swallow mouthwash, because it damages the body.

It is preferable not to rinse one’s mouth with water on fasts. If it is necessary (if one feels discomfort), one may be lenient, with the exception of Yom Kippur. One must be careful not to swallow the water.

Sources: See Shulchan Aruch 567:3; Darkei Moshe1; Eliyah Rabba 5; Be’er Heitev 5; Chayei Adam 132:20; Aruch Hashulchan 3; Mishnah Berurah 11; Kaf Hachaim 14; Toras Chaim 12; Dovev Meisharim 1:124 (most permit rinsing one’s mouth with water in times of need even on Tisha Be’av, but not on Yom Kippur). Concerning mouthwash, see Be’er Moshe vol. 8, permitting rinsing even on Tisha Be’av.

4 Responses to “Rinsing Mouth on Fasts”

  1. If using mouthwash, what could go wrong on yom kippur? As the Rav said, it is damaging to the body, so why is there any fear that a person will swallow it?

    • Some are concerned that mouthwash is considered rechitzah (see R. Shimon Eider’s Guide, quoting from Rav Moshe Feinstein, p. 17). Even if we are lenient for this regarding Tisha Be’Av, we would not be lenient concerning Yom Kippur. Others mention that on Yom Kippur it is forbidden (rabbinic) to consume even foods or drinks that are not worthy of consumption, which is another reason why Poskim are generally unwilling to give permits for using mouthwash on Yom Kippur. Mateh Efraim, indeed, prohibits the practice.

  2. Is brushing teeth with toothepaste the same as mouthwash on fast days where melacha is permitted?

    • Yes, brushing teeth is the same.

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