Functional Medicine: What It Is, How It Works and Who Practices It

Information only, not medical advice. For emergencies call 911 (in the US). New, serious or worsening symptoms need a doctor first, and no program should replace diagnosis or treatment from your regular medical team.

How its supporters describe it

• The Cleveland Clinic's Center for Functional Medicine is quoted by the AAFP as defining it as "a personalized, systems-oriented model that empowers patients and practitioners to achieve the highest expression of health". [1]
• The Institute for Functional Medicine (IFM) describes an "individualized, patient-centered, science-based approach" to underlying causes, as quoted by a critic. [2] IFM's own pages blocked our access (HTTP 403), so we could not read them directly.
• The Cleveland Clinic center says "the foundation of functional medicine is the use of food as a first-line therapy", combined with lifestyle and behavioral interventions. [3]

A 2026 review by Yale and NYU authors describes the model's premise as chronic disease reflecting "disturbances in biological function", with individualized "root causes" sought through systems-based assessment, specialized diagnostic constructs and nonstandard laboratory testing. [4] The review also says it is often confused with integrative medicine, which it calls a different model. [4]

NCCIH adds that the term sometimes means something like integrative health and sometimes something closer to naturopathy. [5] See integrative, functional and lifestyle medicine for the side-by-side view.

What care looks like, as described

Descriptions come from clinics and published studies, not from one standard.

• Visit format. The Cleveland Clinic center lists in-person and virtual one-on-one and shared medical appointments. [3]
• Typical elements in studies. A diabetes trial combined intensive lifestyle changes and tailored dietary supplements with usual care. [6] A trial among health workers tested an elimination diet with five health-coaching sessions. [7] A Vanderbilt program for people with inflammatory bowel disease paired a supervised 6-week elimination diet with education on lifestyle factors. [8]
• Testing. Critics and reviewers describe heavy use of specialized laboratory tests; see testing and treatment plans.

We do not give diets, supplement doses or protocols here. Any plan should come from a clinician who knows your history, and diets and supplements should be reviewed against your medicines. See medication and supplement review.

Who practices it, and how it is trained

The licence a person holds (for example a physician, nurse practitioner, naturopathic doctor or dietitian license, where a state grants one) determines legal scope, not the label "functional". Check it with the state board; see choosing a qualified practitioner.

Cost and access

Prices vary and we could not verify any, so none are given. The Yale and NYU review raises concerns about substantial out-of-pocket costs. [4] In a George Washington University case series of 51 people with mild cognitive impairment or early Alzheimer's disease, 29 stopped within a year, most often because of cost, program complexity and lack of caregiver support. [10] Ask for written costs, including tests and supplements the clinic sells, before you begin; see costs, packages and supplement sales.