We see injuries often enough in the films (1st movie, plus movies 5 and 6, at least one TV episode), a sickness in the 4th movie, and a minor ailment in the 9th film.
Now, we have seen that certain characters know some things about illnesses (the old one in movie 4), and they might be able to pass on certain pieces of information, such as "eat (this plant) and you will recover from (this illness)", but they probably don't know how the plants act as medicine...