(א) אָסוּר לְאָדָם לַחֲבל בֵּין בְּעַצְמוֹ בֵּין בַּחֲבֵרוֹ. וְלֹא הַחוֹבֵל בִּלְבַד אֶלָּא כָּל הַמַּכֶּה אָדָם כָּשֵׁר מִיִּשְׂרָאֵל בֵּין קָטָן בֵּין גָּדוֹל בֵּין אִישׁ בֵּין אִשָּׁה דֶּרֶךְ נִצָּיוֹן הֲרֵי זֶה עוֹבֵר בְּלֹא תַּעֲשֶׂה שֶׁנֶּאֱמַר (דברים כה ג) "לֹא יֹסִיף" (דברים כה ג) "לְהַכֹּתוֹ". אִם הִזְהִירָה תּוֹרָה מִלְּהוֹסִיף בְּהַכָּאַת הַחוֹטֵא קַל וָחֹמֶר לְמַכֶּה אֶת הַצַּדִּיק:
It is forbidden for a person to injure anyone, neither his own self nor another person. Not only a person who causes an injury, but anyone who strikes a Jew in good standing, whether a minor or an adult, whether a man or a woman, in a way of nitzion/bizayon violates a negative commandment, as is stated (Devarim 25:3)...
אלא האי תנא הוא דתניא אמר ר"א הקפר ברבי מה ת"ל (במדבר ו, יא) וכפר עליו מאשר חטא על הנפש וכי באיזה נפש חטא זה אלא שציער עצמו מן היין והלא דברים ק"ו ומה זה שלא ציער עצמו אלא מן היין נקרא חוטא המצער עצמו מכל דבר על אחת כמה וכמה:
Rather, it is this tanna, as it is taught in a baraita: Rabbi Elazar HaKappar the Distinguished said: What is the meaning when the verse states with regard to a nazirite: “And he shall atone for him for sinning by the soul” (Numbers 6:11)? And with which soul did this person sin by becoming a nazirite? Rather, in that he afflicted himself by abstaining from wine. And are these matters not inferred a fortiori: And just as this person who afflicted himself by abstaining only from wine is nevertheless called a sinner, one who afflicts himself by abstaining from everything, through fasting or other acts of mortification, all the more so?
בִּתְלָתָא בְּשַׁבְּתָא מַאי טַעְמָא לָא? מִשּׁוּם דְּקָיְימָא לֵיהּ מַאְדִּים בְּזָוֵוי. מַעֲלֵי שַׁבְּתָא נָמֵי קָיְימָא בְּזָוֵוי! כֵּיוָן דְּדָשׁוּ בֵּיהּ רַבִּים — ״שׁוֹמֵר פְּתָאִים ה׳״.
The Gemara answers: Since the multitudes have already trampled it: “The Lord protects the simple” (Psalms 116:6) applies in this case.
Rabbi Moshe Feinstein (1895-1986; Igros Moshe C'M 2:66)
I was asked by a young woman who wanted to beautify herself so that it would make people eager to marry to her via surgery, whether it would be forbidden due to the prohibition to inflict harm to one's self...Rambam (Chovel 5:1) defines it as either done violently/destructively or according to a different variant of the text in a way that is degrading, see there. Therefore, in this context that the wound leads to beautification it's not destructive or degrading it can't be forbidden...it can certainly be considered for her benefit, and it would be permitted to inflict a wound in order to beautify...indeed it is clear from the incident in Bava Kamma 91b that when there is a reasonable and practical need there is no problem, so too here if it is beneficial for her and she desires it... Perhaps even if this understanding of Rambam is incorrect, but from Sanhedrin 84b, and Rashi there, we see that medical procedures undertaken by most people because it is understood to be beneficial to the extent that it is normative, it is self-evident that it is permitted...It is naturally considered normative behavior for women to want to feel beautiful.
Rabbi Mordechai Yaakov Breish (1895-1976; Chelkas Yaakov C"M §31)
A young woman asked if it would be permissible for her to get a rhinoplasty to make it easier for her to get married...there are two possible issues: a) the injunction against wounding one's self, and b) various surgical procedures are assumed to have intrinsic risks associated with them, and it is forbidden to enter into dangerous situations unnecessarily...We find the Rama rules (Y"D 241:3) that even without mortal danger one is allowed to alleviate pain/distress for their parents with a surgical procedure [see Meiri to Sanhedrin 84b]. Furthermore, we can extend the definition of legitimate distress based on Tosafos (Shabbos 50b) who rules that there is no greater distress than one who [due to a wound or deformity] is embarrassed to go out in public. In both cases, there is not any prohibition of wounding...
Therefore, in this situation there are two factors, it is likely that she is embarrassed to be in public in her social circles...and since we find that oftentimes people discriminate based on a women's beauty, there is no greater distress than this, so we have the straightforward halacha, that a medical procedure done to alleviate distress is permitted and is not a problem of wounding...
Although we find poskim (Avnei Nezer Y"D 321) who say that every surgical procedure is by default considered dangerous, certainly it depends on the time, place, and circumstances...
Additionally, we find in the Gemara regarding risky situations that contain a degree of danger, that once the general populace have trampled it, we apply (the verse) Hashem guards the simple...So here as well since the general populace have already trampled to go to doctors even if the surgery is dangerous, Hashem guards the simple. And our eyes have seen that the vast majority of those who are sick that undergo surgery (May Hashem save us) are healed.
Rabbi Shlomo Zalman Auerbach (1910-1995; Minchas Shlomo II 86:3)
In short, what seems reasonable to me, is that in this situation where it's not done for aesthetic reasons but due to distress, e.g. that his nose is extremely different than any other person, and he is embarrassed because of it, there is room to be lenient...for this reason the custom is to be lenient to dye or pluck white hairs from dark hair for a young man, for example according to his age it is similar to a blemish, and his intention is simply to remove the blemish in order to be like everyone else...however, at least regarding the prohibition to wound, doing it purely for aesthetic purposes wouldn't be a violation, as for him it is considered constructive.
Rabbi Eliezer Waldenberg (1915-2006; Tzitz Eliezer vol. 11:41)
"Charm is false, and beauty ephemeral" (Mishlei 31:30), and anyone who awareness of Hashem touches her heart won't be fooled by the fervor to do plastic surgeries for aesthetic and beauty alone...it is not for a person to decide to outsmart the natural order with such methods, this is like saying to the Artisan that made you, "how ugly is this vessel that you crafted" (Taanis 20b)...therefore it seems the halacha is that it is forbidden for one to undergo plastic surgery, and similarly for a doctor to perform such a surgery, for aesthetic considerations.