Are there any sources discussing (both l'kula and l'chumra) experimental drug studies? Two reasons this would be halachically problematic:

  1. Drugs assigned based on animal studies have a small chance of successfully curing the patient, and a significant chance of causing harm.
  2. Correct dosages are often determined by raising dosages until 50% of patients experience some toxic effect. In this sense, there is a kavua 50% chance of inflicting harm at this stage of the study.

Sources directly discussing this question, or sources on other topics that you think would be relevant are welcome. Hebrew preferred.

  • 1
  • Terrific source - thanks! My main question, which is not quite answered here, is: can we administer a treatment with serious risk to the individual, for the benefit of the research program which could save a multitude of others?
    – user67771
    Jan 5, 2015 at 22:04
  • Which side of this would be l'kula and which would be l'chumra?
    – Daniel
    Jan 5, 2015 at 22:13
  • Do you know how widely the 50% standard applies? Because I recall reading about an exceptionally effective hepatitis C drug that was nixed in 2008 after phase II trials showed signs of liver toxicity in 8% of patients (which is lower than the rate of liver damage from the disease itself).
    – Fred
    Jan 5, 2015 at 23:42
  • @Daniel, good point. I meant to say "pro or con".
    – user67771
    Jan 6, 2015 at 0:27

1 Answer 1


Rabbi Dr. Akiva Tatz discusses general principles of medical halacha in this lecture. Here are some things that he said that are relevant to your question:

A person is obligated, as a patient, to get the best medical treatment that he can. A doctor is obligated to give the best medical treatment available.

(~50 minutes) You're only allowed to pursue medicine that is widely accepted by broad selections of your generation. That said, what is the definition of "widely accepted"? Conventional Western medicine clearly fits the bill. However, it's not perfect -- there are some things that it's "shockingly poor at." You're allowed to do it, because it's an accepted standard. Homeopathy (though it may not always make sense) is "broadly enough accepted that it's permissible."

(~54 minutes) The first thing to consider is the practical -- has all the homework been done? It's not a good idea to be the first person to use a drug that hasn't been researched properly, to put it lightly. However, according to Rabbi Moshe Feinstein*, if (1) the homework has been done and (2) there is a consensus of expert medical opinion that this is worth the risk, a person is allowed (though not required) to pursue an experimental cure.

Although, of course, these are just the basic rules, and each case needs to be investigated by a rabbi on its own merits.

I strongly recommend that you listen to the lecture; if not for the content, then for Rabbi Tatz's wonderful South African accent :P

* Possibly the teshuva mentioned in my answer here.

  • Note that in that lecture, he uses very broad terms and doesn't go into specifics all that much (and no sources :(), but I think this is enough to answer the question.
    – MTL
    Jan 11, 2015 at 5:13
  • This lecture may also be relevant, but I haven't listened to it yet.
    – MTL
    Jan 11, 2015 at 5:14
  • Thanks! I too would be very happy to find that R' Moshe teshuva.
    – user67771
    Jan 12, 2015 at 16:51
  • @user67771 I may have located the teshuva; see my revised answer. It's not exactly what Rabbi Tatz said it was, so in actuality it's probably not the correct one.
    – MTL
    Feb 15, 2015 at 21:18

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