Maimonides (1135 -1206) wrote extensively on medicine, as a physician and as a Rabbi, knowing that we need a good health to better serve God.
Maimonides, for example, recommended avoiding medicines for minor temporary illnesses and depend more in the self regulatory action of our body's nature.
The following examples on the subject are taken from the biographical book: 'Maimonides' by Joel L. Kraemer. (p. 453-454)
Sometimes it is better to let nature run its course.
Even if a person is scrupulous about his diet, there is no way to avoid minor illnesses. The digestive system may be irregular, or one may have a headache or pain somewhere or any other minor ailment. In these cases one should not be hasty to take medications. Rashness, according to ancient medicine, reveals incapacity and ignorance.
If you medicate minor ailments, you either go contrary to your nature or accustom your body to being passive and in need of external assistance. Sometimes, nature will find the way to cure by itself and nature does what is necessary because it is well trained and educated.
It is best to refrain from interfering with nature when life is not in danger, as medications lower the body's resistance. One should rather follow a healthy regimen, Maimonides advised.
Obviously, a patient should not decide to take medications or stop taking medications by himself. In order to decide which illness should be considered 'minor' and left alone and what illness should be treated with appropriate medication, one needs to follow the instructions of his or her physician.
Rabbi Yosef Bitton. YMJC 130 Steamboat Rd. Great Neck NY 11024