Careful Care for a Wound
In Parshas Ki Sisa, Shabbos plays a central theme. It is necessary to constantly review the intricacies of Hilchos Shabbos to ensure that we keep Shabbos in the ideal way. While the Torah forbids 39 main categories of Melacha on Shabbos, there are subcategories delineated in Chazal as offshoots of the main melachos that are also prohibited. Sechita, squeezing (non-food items) is forbidden on Shabbos either as a subcategory of Dash, pressing, or Libun, cleaning. In Orach Chaim 320,17, the Mechaber rules that one may not use a sponge on Shabbos unless it has a handle. The reason is, that it is inevitable to use the sponge without (unintentionally) squeezing out the liquid held in the sponge. As such, it is forbidden even when the issur is performed unintentionally (psik reisha).
This Halacha is pertinent when applying wound care in non-pikuach nefesh situations. The classic dipping of a cotton ball in alcohol to cleanse a wound is forbidden based on the above Halacha. In Nishams Avraham (320,17;1), Rabbi Dr. Abraham rules that even using tweezers to hold the cotton ball would not satisfy the halachic requirement of a handle, and thus doing so is forbidden as well.
Instead, Nishmas Avraham offers two solutions to apply wound care in a Shabbos-friendly manner. Preferably, one should use a nonabsorbent wipe such as nylon to clean the wound. Doing so would avoid all issues of sechita while cleaning the wound in the usual manner. If such material is unavailable, it is preferable to pour the alcohol or other disinfectant directly onto the wound and then use a wipe to clean it off. Doing so changes the Halachic definition of the action from squeezing to drying. Consequently, it is mutar to clean a wound in this manner. Even when applying the liquid first, it is ideal to use a synthetic material to clean the wound because Biblically, only natural materials are subject to the issur of sechita.
The guidelines above follow the opinion of most Poskim. However, Nishmas Avraham does quote a Tzitz Eliezer who permits cleaning a wound in the typical fashion of dipping a cotton ball into alcohol. As in all instances, one should consult their Rabbinic authority before making any Halachic decisions.