Medieval doctors get a bad rep at times. With medical knowledge not as advanced as we know it today, they were working with limited knowledge and instruments. However, not all of their ministrations were bad. There is a running joke in history that if you wanted to hasten your death, just to call a doctor. There were things such as instruments not being cleaned between visits and other practices, which could prove deadly for the next person treated.
Many doctors in medieval times would “bleed” a patient. This was viewed as drawing foul humors out of the blood, and as a way to remove some of the bacteria that were lingering in the body as well. Although some of the practices that they held we view with disdain today, they were working with the best knowledge they had at the time. This was done by cutting a vein, or by the use of leeches on the body. A certain amount would be taken, and then the wound bound, or the leeches removed.
Many of the medicines that they used were herbal in nature, although some were from poisonous plants, when used in smaller doses they worked for the desired results. After the beginning of the Crusades in the Holy Land, some of the medical knowledge that was held by the Middle East began to make its way back to the continent, where they were embraced by the physicians.