Some Laws of Yom Kippur
All are obligated to fast on Yom Kippur, including pregnant and nursing women. Any woman whose health is at risk due to the fast should consult a prominent Torah scholar who is well-versed in these laws and he should render his ruling whether or not she must fast. One whose medical condition does not allow him to fast may not be stringent and fast, for our holy Torah writes, “That he shall live by them,” and not that he should die by them. One may not cause himself to die or even place himself in a possibly dangerous situation because of the fast of Yom Kippur. When Maran zt”l served as Chief Rabbi of Tel Aviv and for several years after this as well, he would spend the precious hours of every Erev Yom Kippur by travelling to the hospital in order to convince patients whom the fast of Yom Kippur posed a danger to not to fast. He would quote the words of the Radbaz who writes that one who does not listen to doctors claiming that he places his complete trust in Hashem is a pious fool, for the Torah gives doctors permission to heal and by default, one must follow the rules of medicine after consulting with a prominent halachic authority.
One Suffering from an Illness which in Essence does not Pose any Danger
We should point out that even if one suffers from an ailment which in essence is not necessarily life-threatening, nevertheless, sometimes the medications one takes make it necessary for one to drink, and if one does not, this may pose a danger to him. In such a situation, the patient should consult his doctor and a prominent halachic authority to discern the proper course of action. This situation is common in patients taking medications for mental illnesses; indeed, sometimes, some of these illnesses can be considered life-threatening in and of themselves.
One who Must Eat on Yom Kippur
If one must eat on Yom Kippur due to an illness, if he must eat and drink in a regular manner, he may do so, as the is nothing that stands in the way of a life-threatening situation. Nevertheless, usually this is not the case and one can make do with eating or drinking in a way that he does not consume large amount of food or beverage in one shot. Rather, one should take breaks between eating and every time he eats or drinks, he should consume no more than thirty grams of food or forty grams of beverage. After approximately ten minutes have elapsed, he should eat or drink a similar amount. One should prepare organized and measured portions of food of approximately thirty grams before Yom Kippur. One should prepare himself a utensil that holds approximately forty grams of liquid (such as a baby bottle, shot glass, and the like) and every time one needs to, one should fill it up and drink from it.
Washing and Immersing One’s Self on Yom Kippur
One may not wash himself with water on Yom Kippur. Even to place one’s finger into water is prohibited. Nevertheless, only a pleasurable washing is prohibited; however, if one’s hands or any other body part were soiled from mortar and the like, one may wash them, as this does not constitute a pleasurable washing. Immersing one’s self in a Mikveh is also forbidden on Yom Kippur.
On the morning of Yom Kippur, one should wash his hands only until his knuckles. One should wash each hand three times while switching off hands and recite the “Al Netilat Yadayim” blessing, as he would any other day of the year.
One should not wash his face on the morning of Yom Kippur; if one’s face is dirty due to eye residue and the like, one may wash the dirty place. If one is finicky and cannot relax until he has washed his face in the morning, he may do so on the morning of Yom Kippur. Ashkenazim are stringent in this matter and rule that even one who is finicky cannot wash his face; rather, he can only wash off the dirt around his eyes and the like.
One may not brush one’s teeth on Yom Kippur. Even one who acts leniently and bushes one’s teeth carefully on Tisha Be’av may not do so on Yom Kippur at all.