Medicine is a substance (not a device) that is used in treatment of conditions of the human body. Medicines are used to relieve pain, prevent progression of disease or alleviate the symptoms of conditions. In the area of infectious disease, they may cure the illness. Examples where medications allow resumption of normal body functions would be treatment of diabetes, thyroid deficiencies, or sex hormone deficiencies.
Medicines in the United States today are prescribed by experienced clinicians, whose ability to prescribe is subject to state licensing laws. In most states they include Doctors of Medicine, Osteopathy, and Podiatric Medicine (Physicians), Nurse Practitioners, Physician Assistants, and in rare cases, Pharmacists themselves. All clinicians have undergone training, though Physicians have had the most extensive training in a medical school, and have developed an extensive body of knowledge expanded over the years.