The Kitzur Shulchan Aruch was written in the 1800s, based on the Shulchan Aruch, which was written in the 1500s. This chapter discusses the medical treatments of the times, some of which may now be discredited. Here, we only address the permissibility of those treatments on Shabbos, not their medical effectiveness. Please consult your own rabbi regarding matters of medical treatment on Shabbos. In case of serious illness or injury, seek medical attention!
91:13 If a person has an open wound called an aperture on his arm, if the hole closes slightly, he may not put a bean in it, because his intention is to keep it open; a bandage that was prepared before Shabbos may be placed on the aperture simply to protect it. However, if one knows that the bandage will squeeze out pus or blood, it is prohibited. Similarly, if he went to wipe it but he knows that wiping will cause blood or pus to come out, he may not do so. This is unlike opening an abscess because when one presses on an abscess, the pus and blood are separate from the flesh and don’t make a bruise; in the case of the aperture, the pus and blood are absorbed in the flesh, so if they are extracted, it will make a bruise.
91:14 If a wound has healed, one may put on it a bandage that was prepared before Shabbos for the purpose of protecting it. One may remove the scab on the wound.