Even with proper pre-fast hydration and caffeine reduction, I almost always get a headache starting around hour 20-22 of a fast and growing from there. Taking a nap is sometimes possible and sometimes helps a little, but not always. (And on Yom Kippur I sure don't want to risk oversleeping and missing part of neilah.)

Is there anything else I can do on the fast day when the headache starts to reduce its effects?

(Even if I had a heter to take medicine (which I don't), all painkillers that I'm aware of do bad things when taken on an empty stomach, and at that point in the day the stomach is quite empty.)

  • I think I've heard of people taking a slow-release caffeine pill right before the fast, but I don't know what it's called, or whether it's legal and safe.
    – Isaac Moses
    Sep 25, 2012 at 16:19
  • I've heard of such products but never seen this for sale (in the US). I'm also mindful of the article linked in this answer to a question about thirst warning against drinking coffee right before the fast. (Caffeine is a diuretic, after all.) Sep 25, 2012 at 16:23
  • I'm voting to close this question as off-topic because it is not about Judaism but about health. Consider asking it on health.stackexchange.com note the tag: health.stackexchange.com/questions/tagged/fasting.
    – mevaqesh
    Dec 16, 2016 at 15:44
  • T. Etoricoxib 120 mg before the fast but consult your physician before to check if there is no contra-indications for you.
    – kouty
    Dec 18, 2016 at 7:52
  • kollel.com/fasting-pills
    – SAH
    Jun 26, 2017 at 18:00

5 Answers 5


The Toronto Kollel has developed a sustained-timed release caffeine capsule which is taken before the ta'anis and begins to release 8 to 10 hours later.

It has been available for many years and literally has thousands of satisfied repeat customers for tisha b'av and yom kippur. They also have the same in ibuprofen, ASA and acetaminophen.

For a distributor in your area e.mail [email protected] or call 1 888 2kollel [2565535] - it is widely distributed in the USA.

The Rosh Kollel, Rabbi Shlomo Miller Shlit"a is a reknowned posek and he permits taking it on shabbos as in this year tisha b'av begins immediately after shabbos.

  • Do you know why taking it on Shabbos wouldn't be considered a form of hachana (forbidden preparing on Shabbos for the week)? Does it need to be mixed in food before Shabbos?
    – Loewian
    Jul 1, 2018 at 21:52
  • hachana is only when I can do it after shabbos and do it on shabbos.but when takes it on shabbos they may NOT SAY that it is for after shabbos Jul 3, 2018 at 0:07
  • Please note this is not FDA approved.
    – user6591
    Oct 2, 2019 at 20:04
  • This is a supplement,not medication and doesn't require FDA approval. Oct 4, 2019 at 4:56

How are you preparing for the fast?

The 4 worst things to eat before a fast:

  1. Cheese and dairy
  2. Eggs
  3. Meat
  4. Potatoes and sugar

And I bet a lot of people eat those things. The problem with the first three is the high protein (and high salt in the case of cheese) require a LOT of water to digest, this makes you thirsty and dehydration causes headaches.

Potatoes and sugar digest extremely fast, which leave you hungry quickly. (To the body potatoes are basically indistinguishable from sugar despite being called vegetables.)

The best things to eat are:

  1. Complex carbs
  2. Fiber
  3. A small amount of fat/oil

Beans/Lentils and other legumes and whole grain products are ideal. Bread is good too. I would add a small amount of fat (whatever you would normally use to cook with). (So a bean/barley/pea soup is perfect - but don't overdo the salt of course.) Salad is surprisingly good - lots of water and fiber (but don't overdo it, you need some calories too). Cooked vegetables should round out the meal.

Do not try to stuff yourself with calories - you need less than you think. What you need to worry about it water.

Next is pre-fast preparation:

How much water do you normally drink during the day? On a fast day your body will expect that much. If you normally drink 8 cups a day you will be in trouble. You need to start reducing your water intake a week before the fast starts.

Basically you want your urine to always be yellow (light yellow is OK) before the fast. Then your body is accustomed to conserving water and will do well with the extra you give it before the fast.

But you can't just drink water - it'll come right out again. You need to mix it with food to slow down the absorption. Your blood is unable to hold much water, you must hold it in your stomach and intestines, and the only way to do it is to absorb it into food - that's why salad is good. So is soluble fiber.

It should go without saying that you should avoid all caffeine for a week before the fast.

For further reading see this study: http://www.ima.org.il/FilesUpload/IMAJ/0/60/30277.pdf (Which, reading between the lines, appears to have been done on frum people.)

  • Thanks for the advice. Your answer might be a better fit here, which is a question about avoiding thirst. My question is about dealing with the headache that, at least for me, seems to show up no matter what I do in advance. (I've tried a bunch of different approaches, including what you describe, but I always seem to get the headache anyway. So while I figure out prevention I'd like to know how to deal with it when it shows up.) Sep 27, 2012 at 3:34
  • 1
    @MonicaCellio Headaches (usually) come from two things: Thirst and caffeine withdrawal. If you skip breakfast and maybe lunch too on an ordinary day, but drink water and have coffee do you get a headache? (If you don't know, then sounds like an experiment is in order.)
    – Ariel
    Sep 27, 2012 at 3:49
  • I drink a lot of both water and caffeine over the course of a typical day, and don't always get breakfast and lunch. I don't get headaches on those days. I don't know if that's due to staying hydrated or the caffeine maintenance. I ramp the caffeine down to zero in advance of Yom Kippur, BTW. (Why don't I keep it there and give up caffeine? Sleepy! :-) ) So I've been assuming that the YK headache is primarily due to dehydration, though maybe I'm kidding myself that a week of caffeine reduction helps. Sep 28, 2012 at 2:42
  • @MonicaCellio In that case your headache is not from not eating, it's from dehydration and caffeine. Are you at zero caffeine for at least 3 days before Yom Kippur? And follow my pre-fast plan to help with the dehydration.
    – Ariel
    Sep 28, 2012 at 3:09
  • I will say that there was a fast day where I saw midway through that my then small headache would inevitably become a big headache, so I had one small cup of coffee. I felt great for the balance of the day. Apparently, my headache comes from caffeine (and maybe dehydration). May 24, 2013 at 4:14

CYLOR, but I have heard of people taking caffeine suppositories on Yom Kippur.


Rav Chizkiyahu Nevenzahl Shlit"a, current Chief Rabbi of the Old city permits swallowing pills without water on a fast day (including Tisha B'av and Yom Kippur) because swallowing is not considered derech achila - the normal way of eating, of which is prohibited on a fast day .

This is not to be relied upon for practical halacha

  • Rav Shmuel Kamenetsky קובץ הלכות בין המצרים פרק ב' הלכה ח allows it as well, with small amount of water [less than a shiur] if necessary. This is not for Yom Kippur. Jul 1, 2018 at 20:22

A couple of years ago I stumbled on an unorthodox approach to the caffeine problem. Now that I've been through several full-days fasts with it, I'm confident in reporting my results. Of course, I don't have broad data and thus can't account for any quirks of my own physiology, but here's what I know.

This article about how long caffeine stays in your system has this tidbit that caught my eye (emphasis mine):

The dosage of caffeine consumed can impact how long it stays in a person’s system. Someone who ingests low dose (especially relative to their body mass) should clear caffeine from their body quicker than someone who ingests a high dose. Though other factors play a prominent role in clearance, the body can only metabolize and excrete a set amount of caffeine at a time; if this threshold is exceeded – metabolism and clearance is compromised. [...]

A heavy caffeine consumer may ingest over 400 mg per day (equivalent to 4 cups of coffee). At this point, enzymes in the liver may be overtaxed and more caffeine (and its metabolites) may accumulate within the body. This accumulation may prevent efficient clearance and result in reabsorption, prolonging excretion times relative to dosage consumed.

Oh really? Maybe I'd been doing it wrong.

The answer for me turns out to be: don't ramp down the caffeine to zero in advance of the fast; boost it on the day leading into the fast. I've found that 4-5 cups of coffee or equivalent does the trick. (This is more than I usually drink, but not vastly more.) Because caffeine is a diuretic you have to be careful to accompany that with plenty of water or fruit juice to prevent dehydration. But since I started attacking the caffeine problem by increasing the pre-fast dose instead of withdrawing, I have not had a caffeine headache on a fast day.

You're probably wondering if I sleep that night. Yes. I always sleep a little fitfully on the night of Yom Kippur because of the themes of the day, but I still sleep. Because I'm a regular caffeine drinker I probably have somewhat of an immunity; I can drink a cup of coffee and then go to sleep normally. I wouldn't recommend this approach for a light caffeine user, but a light caffeine user also probably does not have the withdrawal-headache problem.

  • 1
    Similar to what I've done. I slowed down caffeine intake over a week, and took coffee right before the fast.
    – HaLeiVi
    Sep 20, 2018 at 3:11

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