It is forbidden to eat or drink anything on Tishe Beav.
One who is sick: A person who is sick and needs to eat is not required to fast on Tishe Beav as the Sages did not institute the fast for those that are sick. If he needs to eat he is required to break his fast. [Anyone who feels weak and sick to the point he is bedridden is considered sick in this regard even if it is not life threatening.]
Pregnant and nursing women: A pregnant or nursing woman must fast on Tishe Beav just like on Yom Kippur. [If however a pregnant or nursing woman feels weak and will become sick due to the fast, she is not to fast. If a pregnant woman begins to feel dizzy or labor contractions or low/high blood pressure she is to break her fast. Certainly if she feels sick and needs to lie in bed she is to break her fast. The same applies for a nursing woman. If a nursing woman feels healthy but she will not have milk for her child if she fasts then if her child only eats from her, she may break her fast. Some Poskim rule that this applies even if she is able to try to feed the child formula and the like, that nevertheless she is not required to do so. Practically such a woman is to contact a Rav for a final ruling. Some Poskim are lenient for all pregnant women that are prior to their 9th month, to not fast if it is very difficult due to the hot weather. Practically such a woman is to contact a Rav for a final ruling.]
A woman who is after childbirth: A woman within 30 days of childbirth is not required to fast. Nevertheless, the custom is to fast unless she is experiencing great pain in which case there is worry of danger. Nonetheless a woman may choose to be lenient against this custom and not fast within thirty days of birth even if she is not in pain. [Practically in today’s times all women within thirty days of birth are to be taught not to fast. Certainly if she is within seven days of birth or even more so within three days of birth, it is forbidden for her to fast.]
Taanis Nidche: If the fast fell on Shabbos and was hence differed to Sunday, one may be lenient not to fast even if he or she is a slightly sick, and is not bedridden.
When exempt from fasting, as stated above, must one nevertheless try to fast as many hours as possible?
No one who is exempt from fasting may eat immediately in the morning. Nevertheless if possible one is try to fast at night at least until the morning.
May one who is sick take medicine?
One who needs to take medicine on Tishe Beav may do so even if he is not sick. If one is sick then he is not required to fast, as explained above. Even if one is not sick, it is permitted to do so if the medicine is bitter. He is to swallow it without water or alternatively place something bitter in the water and use this water to help swallow the pill. [If one is unable to do so, then the medicine may be taken if the person will fall sick if he does not take it.]
Is one to wash hands as usual when eating bread on Tishe Beav?
Does one who eats bread on Tishe Beav recite Nachem in Birchas Hamazon?
Must one who is not fasting say Havdala prior to eating?
Yes. This includes men and women.
What is the Seder of Hvadala in such a case? One omits the versus of “Hinei Keil Yeshuasi”, and rather begins from the blessing of Hagfen or Shehakol [depending on his beverage]. The blessing of Besamim is omitted. If this Havdala is being recited on Sunday, the blessing of Haeish is likewise omitted and is supposed to be said the night before.
Is wine to be used or Chamer Medina? Some rule one is to use wine or grape juice. Others rule one is only to use Chamer Medina, such as tea or coffee. If there is a child available which has not reached the age of Chinuch for mourning but is past the age of Chinuch for blessings, one may say Havdala over wine and give him to drink.
 Michaber 554/6
 “He is to be fed immediately” [Michaber ibid]
 See M”B 554/11
 Michaber 554/5
 Aruch Hashulchan 554/7; Piskeiy Teshuvos 554/5
The reason: As she is considered like a sick person.
 Piskeiy Teshuvos ibid; and so I received from Harav Asher Lemel Hakohen
 Piskeiy Teshuvos 554/6
 See Shaareiy Teshuvah 554/14 in name of Machazik Bracha
 See Piskeiy Teshuvos 554/6 in name of Chazon Ish that she does not need to try giving him formula and the like as mother’s milk is the healthiest food for a child. However certainly if the child has already been given formula before, and consumed it, then she must try to do so for Tishe Beav as well.
 Rav SZ”A in Halichos Beisa 25/2; Tzedaka Umishpat Hakdama; See Nitei Gavriel 65 footnote 2
 554/6; For a further understanding of such cases see also SH””A chapters 617-618.
 Michaber ibid
 Rama ibid
 Aruch Hashulchan 554/8 “Today heaven forbid a woman after birth to fast on Tishe Beav as they are weak and are certainly sick and therefore they are not be allowed to fast”; Piskeiy Teshuvos 554/7; so I received also from Rav Asaher Lemel Hakohen
 M”B 554/13
 Shvus Yaakov 3/37; Hagahos Rav Akiva Eiger 559/9; Biur Halacha 559 “Eino”; Nitei Gavriel 65/3; Piskeiy Teshuvos 554/5; See Yechaveh Daas 3
 Piskeiy Teshuvos 554/9
 Kaf Hachaim 554/34 in name of Kesonos Yosef 4; Ikarei Hadaat 29/36; Tosefes Chaim on Chayeh Adam 1/135-8; ; Piskeiy Teshuvah 567; Pischei Olam 554/6; Piskeiy Teshuvos 554/7; 568/3
 Igros Moshe 3/91; Piskeiy Teshuvos ibid
 Kaf Hachaim 554/53
 Rama 587/1 “One who ate on Tishe Beav is to say Nachem in Birchas Hamazon”
 M”A 557/1
 Shaareiy Teshuvah 556/1 in name of Bircheiy Yosef
 Divrei Malkiel 6/9; Piskeiy Teshuvos 556/4 as is the ruling by an Avel; Regarding an Avel-see Pischeiy Teshuvah 376/2; 391/1 Piskeiy Teshuvos 296/6
 Bircheiy Yosef ibid; Shraga Hameir 7/71; Az Nidbaru 11/48
 Kaf Hachaim 556/9; Minchas Yitzchak 8/30; Kinyan Torah 2/111