Sicha Keshtiya: May non-Kosher products [i.e. Shampoo, soap, perfume etc.] be smeared on the body?
General rule regarding using the actual non-Kosher food on body: Some Poskim rule one may smear non-kosher food on his body, so long as it is not forbidden in benefit, and so is the implied opinion of Admur. Other Poskim rule it is [Rabbinically] forbidden to smear non-Kosher foods on the body. This however only applies if one is smearing the product for pleasure purposes. It is however permitted to smear it for medicinal purposes, such as to relieve pain. Practically, the widespread custom is to be lenient, although some are stringent in this matter. Some Poskim conclude that it is proper for every person to be stringent in this matter. [The Chabad Rabbeim were stringent in this matter even regarding soap. This however was not a directive to the public.]
Using inedible non-Kosher products such as soap: Some Poskim rule that even according to the stringent opinion the Rabbinical smearing prohibition only applies if the Issur is edible and not Pagum/inedible, if however, it is inedible then it is permitted to be smeared according to all even for pleasure. Other Poskim however rule that according to the stringent opinion who prohibits smearing non-Kosher foods, the prohibition applies even if the Issur is Pagum. Some Poskim rule that by something that is so Pagum that it is not edible to even a dog then the concept of Sicha Keshtiya does not apply according to any opinion. Practically, the widespread custom is to be lenient, although some are stringent in this matter. [The Chabad Rabbeim were stringent in this matter regarding soap. This however was not a directive to the public.]
Inedible Chametz products on Pesach: Using inedible Chametz products on Pesach follows the same dispute and customary allowance as using inedible non-Kosher products. Nevertheless, some Rabbanim conclude that so is the proper custom to be stringent, as the Arizal states that it is proper to be stringent like all the stringencies on Pesach. The above allowance only applies if the product was produced before Pesach.
Using them on one’s lips or mouth: According to the lenient opinions and widespread custom, it is permitted to use inedible non-Kosher products even in one’s mouth, so long as one does not have intent to swallow the item.
It is proper to avoid smearing edible non-Kosher food onto one’s skin for pleasure purposes. It may be smeared even initially for medicinal purposes. One may smear inedible non-Kosher products on one’s skin, and so is the custom. However, some are stringent in this matter.
There is a general discussion in Halacha as to whether smearing an item on one’s body is similar to eating it, or not. This concept is called “Sicha Keshtiya.” We find regarding Yom Kippur that Sicha is Keshtiya. The question is whether this applies only to Yom Kippur, or to all Issurim. We find several opinions on this matter:
 Implication of Admur 326/10 and Rama 326/10; Nekudas Hakesef Y.D. 117/4 that from letter of law is Mutar; Peri Chadash 117/4; Machazik Bracha 614; Tosafus Yuma 77a and Rashba, Ritva, Tosafus Rosh and Meiri on Nidda ibid; Rashbatz; Beis Yoef 123 in name of Rashba
 See Admur 326/10 “[However] according to those who [held there] that the reason for the prohibition of crushing snow and hail is because of a decree made [to safeguard one from coming to] squeeze fruits which are designated for their juices, and snow and hail are likewise designated for their liquids as was explained there [in 320/19], [then according to them] soap and other Cheilev which are not designated as liquids are permitted to be [even] initially crushed.”
 The reason: As the concept of Sicha Kesh only applies by Yom Kippur, and not by other Issurim even if done for pleasure purposes. [Tosafus Yuma 77a] Alternatively, as it only applies regarding forbidden oils and only when done for pleasure purposes. [Tosafus Niddah 32a]
 Taz 117/4; Issur Viheter 39/34; Semag; Semak; Beis Yosef 117 in name of Orchos Chaim p. 312; Zivcheiy Tzedek 117/45; Gr”a O.C. 326/10
 Poskim ibid
 All Poskim in previous footnote other than Orchos Chaim ibid who does not make a differentiation
 Bach ibid; Nekudos Hakesef ibid; Biur Halacha 326/10 “Veassur” and “Beshaar Cheilev”
 Nekudos Hakesef ibid; Biur Halacha 326/10 “Veassur” and “Beshaar Cheilev” in name of Gr”a O.C. 326/10; M”B concludes custom is to be lenient although best to be stringent
 Nekudos Hakesef ibid regarding soap “some are stringent and so is proper”; Aruch Hashulchan 117/29; Biur Halacha 326/10 “Veassur” and “Beshaar Cheilev” in name of Gr”a O.C. 326/10 regarding using non-Kosher soap; M”B concludes custom is to be lenient although best to be stringent if one is able; Kaf Hachaim 117/15
 Heard from Rav Eli Landa Shlita
 Peri Chadash 117/4; Soles Belula 35/13; Beis David 23; Aruch Hashulchan 117/29; Kaf Hachaim 326/45; 117/17
 Nekudos Hakesef ibid regarding soap “some are stringent and so is proper”; Shevilei David 117/2; Biur Halacha 326/10 “Veassur” and “Beshaar Cheilev” concludes that the custom of the world is to be lenient [regarding soap] and only the meticulous are careful in this. Nevertheless, he concludes that if one is able to purchase Kosher soap then certainly it is proper to suspect for the stringent opinion.
 Aruch Hashulchan ibid seemingly even according to Nekudos Hakesef and Biur Halacha ibid
 Bach ibid; Nekudos Hakesef ibid; Biur Halacha ibid; Aruch Hashulchan ibid
 Nekudos Hakesef ibid; The M”B ibid concludes that the custom of the world is to be lenient [regarding soap] and only the meticulous are careful in this. Nevertheless, he concludes that if one is able to purchase Kosher soap then certainly it is proper to suspect for the stringent opinion.
 Heard from Rav Eli Landa Shlita
 Nitei Gavriel Teshuvah 6 [volume 3 p. 393]; Heard from Harav Eli Landa Shlita that on Pesach the custom is to be stringent in this, in light of the ruling of the Arizal
 Arizal, brought in Shut Admur 6