Our Hachamim forbade doing anything on Shabbat to heal a person who falls under the category of Mihush Be'alma. Mihush Be'alma is a person who doesn't feel a hundred percent but is not bedridden or in any terrible pain. The reason is so that a person will not end up grinding herbs which is forbidden as part of the Melacha of Tohen - Grinding. (See DSH from November 28, 2014.) However, something which is done by healthy people may be done by a person with a Mihush Be'alma as well. For example, since honey is used by healthy people, a person with a sore throat may consume honey too even though he's only having it to heal his throat. There are some Poskim who do allow a person with a Mihush Be'alma to take aspirin or Tylenol and therefore one who is in a lot of pain, may do so. Of course, if there is any life threatening danger, everything possible must be done to save the person.