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!
91:15 A person may remove a splinter using a needle so long as he is careful not to draw blood, which makes a bruise.
91:16 If a person has to go lie down because of his illness but he isn't in danger - or if he has pain that causes him distress and makes him feel ill in his whole body so that he's considered like one who has taken to his bed even though he's still walking around - one may direct a non-Jew to give him medicine and cook for him. (This is only if he actually needs these things on Shabbos - Mishnah Brurah 328:46.) On this Shabbos, he may eat food cooked by a non-Jew, just as the non-Jew is allowed to cook for him on Shabbos. (After Shabbos, a Jew must cook for him as per usual - MB 328:63.)