Some of the most radical changes in medicine came from the Arab world during this period. During this period, pharmacies became plentiful in the Arab world, as people studied the medicinal effects of chemicals and herbs. The Arab world also made advances in the growth of optometry. These benefits would be available to the Christian world only after the Crusades and the beginning of the Renaissance with the fall of Byzantium in 1453, but this falls outside our time period.
The Christian world lagged behind medicine during this time, though there were some notable changes. During times of plague, people practiced quarantine. Universities began to put emphasis on secular matters, including medicine. The growth of medicine began to grow as its own profession. Sometimes the best care to be had at the time came from churches that used herbal remedies. The church monks also wrote their own medical books by hand; while most Europeans could not read, Europe was not totally without medical knowledge. During times of plague, some European doctors even noticed that vinegar warded off the disease, but no one was aware of germ theory, and most people still attributed disease to bad air.