Wikipedia
Medical psychology is the application of psychological principles to the practice of medicine for both physical and mental disorders. The American Society for the Advancement of Pharmacotherapy defines medical psychology as "that branch of psychology that integrates somatic and psychotherapeutic modalities into the management of mental illness and emotional, cognitive, behavioral and substance use disorders". A medical psychologist who holds prescriptive authority for specific psychiatric medications and other pharmaceutical drugs must first obtain specific qualifications in Psychopharmacology. A trained medical psychologist is equated with a mid-level provider who has the authority to prescribe psychotropic medication such as antidepressants for neurotic disorders. However, a medical psychologist does not automatically equate with a psychologist who has the authority to prescribe medication. In fact, most medical psycholgists do not prescribe medication and do not have the authority to do so.
Medical psychologists apply psychological theories, scientific psychological findings, and techniques of psychotherapy, behavior modification, cognitive, interpersonal, family, and life-style therapy to improve the psychological and physical health of the patient. Psychologists with post doctoral specialty training as medical psychologists are the practitioners with refined skills in clinical psychology, health psychology, behavioral medicine, psychopharmacology, and medical science. Highly qualified and post graduate specialized doctors are trained for service in primary care centers, hospitals, residential care centers, and long-term care facilities and in multidisciplinary collaboration and team treatment.