My question is whether or not a commandment can be broken in cases that could prevent an illness (e.g if it was certain that eating pig could prevent a certain type of cancer, consuming freshly crushed herbs on shabbos to prevent a certain disease etc.)?

  • 1
    Theres a big Machlokes HaPoskim regarding the second example Commented Dec 6, 2017 at 20:30
  • 1
    this article(ncbi.nlm.nih.gov/pmc/articles/PMC4624081) seems to give evidence that it does
    – Fei23
    Commented Dec 6, 2017 at 22:09
  • So basically the question is whether even safek pikuach nefesh is docheh whatever, the same way certain pikuach nefesh usually is? If that’s the case, I don’t think this is too broad at all.
    – DonielF
    Commented Dec 7, 2017 at 15:03
  • 1
    " if pikuach nefesh extends to prevention of disease" - I think it's terminology. As I understand pikuach nefesh implies that your life is in imminent danger. It's an emergency. You need to do something immediately. Preventing disease from coming when you are well now is a separate mitzvah of "venishmartem lenafshoteichem" - "guard your life", or in short, do what you can to stay healthy. Using a treadmill is healthy and prevents sickness and disease. It is "prevention",. But you still can't use one on Shabbat or Yom Tov.
    – DanF
    Commented Dec 7, 2017 at 15:31
  • 1
    I would extend @DanF's comment. You're talking about a possibility of prevention. In current state of affair in science we only have a statistical correlation between actions and results. Just like saying "I now have a 23% chance of developing condition X, and if I do Y it lessens to 14%. Should I do Issur Z to benefit from it?"
    – Al Berko
    Commented Dec 10, 2017 at 0:44

2 Answers 2


TL;DR: According to some authorities, future danger to life allows for current intervention that violates biblical halakha if necessary. However, that may only apply in cases where the future danger is likely. In cases where the danger is unlikely, even those poskim might be stringent. Some poskim are lenient in cases where there is a current indication (such as a genetic mutation) that makes it likely that in the future a person will become dangerously ill. This is in between a case of current pikuah nefesh, and future pikuah nefesh.

R. Eliezer Berkovitz notes in Berur Halakha B'din Nittuhei Metim (printed in in Sinai (69 pp. 45-66)) that Sanhedrin (26a) states in explanation of the statement of R. Shimon in Sanhedrin (3:3) that when the tax collectors became abundant, people would work the fields during the shemittah year. Tosafot there (s.v. misherabu) explains in the second answer that if they didn't have have the grain they would be unable to pay their taxes and would be killed. Therefore, it was considered pikuah nefesh and they could violate biblical commands.

It appears that (according to this) in a case where one knows that in the future lives will be endangered, he may take steps now, even in violation of biblical law, to prevent it.

Similarly, the Hazon Ish ruled (YD Hilkhot Avelut 208:7) regarding performing autopsies (otherwise forbidden as mutilation of the dead) to gain medical knowledge to save lives, that it would be permissible even if the theoretical patients whose lives would be saved are not here right now, as long as it is is a common disease, such that it is known that someone in the future will be affected by it.

This is also the opinion of R. Yosef Brandesdorfer in Orah V'Simha to Hilkhot Shabbat (2:23).

For a related discussion see Teshuvot V'hanhagot (3:105).

However, while it is true that according to some views biblical law can be violated now to prevent future loss of life, those cases are apparently cases in which it is very likely that life will be endangered, and in the case of Tosafot, where it is very likely that violating the prohibition will solve the problem. However, although normally even if someone only might be in danger (e.g. a person is buried under rubble and he may or may not already be dead) we allow violation of biblical commandments, and similarly, we violate biblical commandments even where the treatment is guaranteed to be effective, perhaps in cases of future danger to life, the degree of certainty that there will be a danger and and that the treatment would need to be effective, are higher.

Notably, in discussing removal of ovaries and Fallopian tubes from women undergoing hysterectomies, assuming that there is a 5% chance of cancer developing there, R. Moshe Feinstein in Igrot Moshe (HM 2:73) does not mention pikuah nefesh / danger in that case, as a reason to be lenient, except as an afterthought. His primary reasoning only invokes details relevant to that particular case:

ליכא שום חשיבות ושם השחתה על מה שנשארו השחלות וצנורות הרחם והוי זה כצער וחבלה בשאר אבריה שלטובתה אין לאסור

He does mention the possible future danger as more of a reason to be lenient:

וגם הא שעלול להעשות סרטן אף שהוא רק בסך חמשה אחוזים יש להחשיב סכנה להאשה להתיר זה דהוא חשש גדול

There is also a case between imminent pikuah nefesh, and future pikuah nefesh. That is a case in which there is currently a factor that that makes a future danger likely. For example, if an Ashkenazi woman has the BRCA mutation, she can be perfectly healthy, but have a 60% or 40% chance of developing breast cancer, and a 53% or 62% chance of developing ovarian cancer, depending on which mutation she has (ibid). Accordingly, Rabbis Avraham Steinberg, Zalman Nehemiah Goldberg, and Asher Weiss are quoted (ibid) as permitting prophylactic oophorectomy (removal of the ovaries) although according to some there is a biblical prohibition of castration, that according to some applies to females, on the grounds of pikuah nefesh. Although she is not currently sick, her genetic predisposition that she had from birth, is considered sufficient.

  • Still thinking of this :-> You might be interested in my new comments below as well. The BRCA article states that one can perform castration because the risk to human life is imminent. This is a much higher standard than "could prevent an illness" being asked in the OP question.
    – mbloch
    Commented Dec 14, 2017 at 16:28
  • I don't deny that. Nor do I think anything in the post indicates the contrary. @mbloch
    – mevaqesh
    Commented Dec 14, 2017 at 17:05
  • I was not writing in a critical way - I was just sharing - although I do think it strengthens a no answer to the OP (since could prevent an illness is a low bar) - but I think your writeup evolved in a very nice and balanced way, I also +1'ed it
    – mbloch
    Commented Dec 14, 2017 at 18:39

I understand your question as whether taking preventive medicine allows to break commandments, i.e., does preventing future health issues has a status similar to saving lives (pikuach nefesh) which as we know allows to break most commandments.

I also understand that

  • there is an element of probability in there (you write "could prevent an illness"), i.e., the preventive medicine reduces the health risk but does not eliminate it completely
  • the health risk might lead to premature death, or not
  • we are speaking of a healthy person to start with (as the rules for non-seriously ill or seriously ill patients are different)

I will aim to show that there is no opening to breaking commandment for a healthy person who might possibly prevent future health issues this way based on two arguments

  1. Halachic medical leniencies do not apply to normal healthy people
  2. The specific examples (eating forbidden foods, crushing herbs on Shabbat) do have leniencies but, again, they don't apply to healthy people

First one should know the halacha defines a number of categories for sick people: choleh she'yesh bo sakana (seriously ill patient), chole she'eyn bo sakana (non-seriously ill patient), mitztaer (someone suffering from a certain degree of discomfort). Each of these will have different leniencies apply to him, e.g.,

  • one can turn on a light to attend to a seriously ill patient (Nishmat Avraham vol. 1, p. 129) or generally transgress the Shabbat for him (but only as required, ibid. p. 185)
  • the non-seriously ill patient who has already suffered a heart attack can jog on Shabbat if he does so daily to prevent another heart attack (Nishmat Avraham vol. 1, p. 140)
  • one is permitted to ask a non-Jew to perform a rabbinic violation for a mitztaer (see bottom of here)

However these leniencies do not apply to normal healthy people, as such for instance

  • a healthy person who jogs regularly to prevent heart attacks should not do so on Shabbat (Nishmat Avraham vol. 1, p. 140)
  • a patient (i.e., not a healthy person) can only take medication on Shabbat if omitting it would cause him harm, or if he would be cured only by taking the medicine a given number of days incl. Shabbat (Nishmat Avraham vol. 1, p. 177 but Shmirat Shabat K'hilchata is lenient)

As was mentioned in comments, each commandment has certain leniencies but they are relevant to sick people only, e.g.,

  • a seriously ill person can ingest pills containing non-kosher ingredients, even non-seriously ill patients can often eat them as ingesting pills is not defined as eating (see e.g., here and here)
  • one can cut and crush aromatic herbs in order to wave them over the head of a patient (SA OC 322:5)

As such I do not think there is any opening to breaking commandment for a healthy person who might possibly prevent future health issues this way.

The more I think of the question, the more I think the halacha depends on how certain the probabilities are, e.g.,

  • if eating pork saves a life immediately - no question it is permitted
  • if it will for sure save a life in the future - it will very likely be permitted
  • if it might possibly save a life in the future - it will very likely not be permitted

Remember to CYLOR before applying anything you read here to real life.

PS. Nishmat Avraham is a classic sefer on medical halacha, see here

  • @mblock regarding the article I linked in the comments of the OP (ncbi.nlm.nih.gov/pmc/articles/PMC4624081), it seems like for those with risk factors it might be considered pikuach nefesh even though they are currently healthy
    – Fei23
    Commented Dec 13, 2017 at 22:56
  • 1
    @Fei23 I think one has to read the article very carefully because it also states "In general, the saving of human life almost always overrides the commandments when the situation is immediately at hand (le’faneinu). The potential saving of human life, which does not exist at the time of decision-making, cannot override prohibitions." [...] Rabbis X/Y/Z share this view that for a BRCA carrier the prohibition of castration is annulled by the saving of human life, because the BRCA carrier is in a condition of possible danger to life from conception when she inherited the BRCA mutation.
    – mbloch
    Commented Dec 14, 2017 at 16:19
  • 1
    @Fei23 They specifically mention “a clear and present danger”. This might not be the same case as you referred in your question “… that could prevent an illness”. In the article you refer, the case is much clearer: the patient is sick and needs to be healed. In the words of the article “Thus, the Rabbis cited in this article believe that for a BRCA carrier the risk to human life is imminent and the prohibition against castration, or any other prohibition for that matter, may be annulled to save a human life
    – mbloch
    Commented Dec 14, 2017 at 16:20
  • 1
    The case of the article might have been the case you wanted to ask about. I think this is the crux of the issue. If the danger to life is clear/imminent, then one is permitted to break commandments. If it is a possible risk lo lefaneinu then one is not. Hope this helps further our joint understanding of the issue
    – mbloch
    Commented Dec 14, 2017 at 16:22

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .