Functional Medicine is a systems biology–based approach that focuses on identifying and addressing the root cause of disease. Each symptom or differential diagnosis may be one of many contributing to an individual’s illness. The precise manifestation of each cause depends on the individual’s genes, environment, and lifestyle, and only treatments that address the right cause will have lasting benefit beyond symptom suppression. By shifting the traditional disease-centered focus of medical practice to a more patient-centered approach, Functional Medicine addresses the whole person, not just an isolated set of symptoms.