Does the obligation and prohibition only apply by matters of potential danger of life, or even against matters that can cause non-lethal injury?^[1]

Although from some Poskim^[2] it is implied that the obligation and prohibition is only to guard oneself from lethal danger, and not simply to nonlethal injury, nonetheless, practically the Poskim^[3] rule that the obligation and prohibition applies even to guarding oneself from nonlethal injury. [However, it is unclear if this is part of the Biblical prohibition or is only a rabbinical requirement.^[4] Certainly, however, it is forbidden for one to damage his body even in a non-lethal way, as explained in Halacha 3.]

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[1] See Devar Avraham 1:37-25; Shemiras Hanefesh Kehilchasa Chapter 1: Iyunim 3; Sefer Shemiras Haguf Vihanefesh [Lerner] Mavo Chapter 2

[2] Implication of wording of Admur Shemiras Guf Vinefesh Halacha 3 and Michaber C.M. 427:5 and Rambam Rotzeiach 11:4 who specify “Sakanas Nefashos”

[3] Implication of wording of Admur Shemiras Guf Vinefesh Halacha 14 “One is obligated to beware of his body, to not cause it loss, destruction or injury.”; Minchas Chinuch Mitzvah 546-547; Mabit in Kiryas Sefer Azhara 292; Semag L.S. 167; Sefer Yireim Amud Hayirah Mitzvah 44; Tosafos Shavuos 36a; Ben Ish Chaiy Pinchas 2:8; Divrei Malkiel 2:53; Aruch Hashulchan C.M. 427:6

[4] From some of the sources above it is implied that it is part of the biblical prohibition [i.e. Kiryas Sefer; Minchas Chinuch; Semag; Yireim; Aruch Hashulchan], while from other sources it can be understood that it is only rabbinical [i.e. Ben Ish Chaiy] As to the contradiction in Admur, perhaps one can answer that only actual danger of life is included in the biblical prohibition while damage to the body is part of the rabbinical prohibition.