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Overview of Integrative, Complementary, and Alternative Medicine


Denise Millstine

, MD, Mayo Clinic

Reviewed/Revised Oct 2021 | Modified Sep 2022
Topic Resources

Integrative medicine and health (IMH) and complementary and alternative medicine (CAM) include healing approaches and therapies that historically have not been included in conventional, mainstream Western medicine.

CAM is often thought of as medicine that is not based on the principles of mainstream Western medicine. However, this characterization is not strictly accurate.

One key difference between CAM and mainstream medicine is the strength of evidence supporting best practices. Mainstream medicine, when possible, bases its practices only on the most conclusive scientific evidence. In contrast, CAM bases its practices on evidence-informed practices—practices based on the best evidence available, even when such evidence does not meet the highest, strictest criteria for efficacy and safety. However, some CAM practices, including use of some dietary supplements Overview of Dietary Supplements Dietary supplements are the most commonly used of all integrative, complementary, and alternative therapies, primarily because they are widely available, relatively inexpensive, and can be bought... read more , have been validated by traditional scientific criteria.

Defining Complementary, Alternative, and Integrative Medicine

Complementary, alternative, and integrative medicine are terms often used interchangeably, but their meanings are different.

  • Complementary medicine refers to non-mainstream practices used together with conventional medicine.

  • Alternative medicine refers to non-mainstream practices used instead of conventional medicine.

  • Integrative medicine is health care that uses all appropriate therapeutic approaches—conventional and non-mainstream—within a framework that focuses on health, the therapeutic relationship, and the whole person.

IMH aims to combine CAM with mainstream medicine when appropriate. Some CAM therapies are now offered in hospitals and are sometimes reimbursed by insurance companies. Some traditional medical schools, including 70 North American medical institutions in the Academic Consortium for Integrative Medicine and Health, provide education about integrative medicine and therapies.

According to the most recent National Health and Nutrition Examination Survey (NHANES) data, as many as 38% of adults and 12% of children have used CAM at some point, depending on how broadly CAM is defined. A National Health Interview survey (2012) indicates that commonly used CAM therapies include

  • Deep breathing exercises (11%)

  • Yoga, tai chi, and qi gong (10%)

  • Manipulative therapy (8%)

  • Meditation (8%)

  • Yoga (6.1%)

Use of other CAM therapies and approaches remains variable and difficult to quantify: homeopathy (2.2%), naturopathy (0.4%), and energy healing (0.5%). In the US, 57.6% of adults used at least one dietary supplement in the past 30 days.

Patients do not always volunteer information about their use of these therapies to physicians. Therefore, it is very important for physicians to ask their patients specifically about their use of these therapies (including medicinal botanicals and nutritional supplements) in an open, nonjudgmental way. Learning about patients’ use of CAM can do the following:

  • Strengthen rapport and build trust

  • Provide an opportunity to discuss evidence for CAM and its plausibility and risks

  • Sometimes help physicians and other health care practitioners (including pharmacists) identify and avoid potentially harmful interactions between drugs and CAM therapies or nutritional supplements

  • Monitor patient progress

  • Help patients determine whether they should use specific certified or licensed CAM practitioners

  • Learn from patients’ experiences with CAM



In 1992, the Office of Alternative Medicine in the National Institutes of Health (NIH) was formed to study the efficacy and safety of alternative therapies. In 1998, this office became the National Center for Complementary and Alternative Medicine (NCCAM), and in 2015, it became the National Center for Complementary and Integrative Health (NCCIH). Other NIH offices (eg, National Cancer Institute) also fund some CAM research. The NCCIH maintains a list of research outcomes in this field.

There are 3 types of support for CAM therapies:

  • Efficacy on clinical outcomes as shown in controlled clinical trials (considered the strongest evidence for clinical uses)

  • Evidence of established physiologic mechanisms of action (eg, modification of gamma-aminobutyric acid [GABA] activity in the brain by valerian), although evidence of a validated physiologic mechanism of action does not necessarily indicate efficacy on clinical outcomes

  • Use over periods of time ranging from decades to centuries (considered lower quality evidence)

A substantial amount of information about CAM is available in peer-reviewed publications, evidence-based reviews, expert panel consensus documents, and authoritative textbooks; much of it has been published in languages other than English (eg, German, Chinese). Many CAM therapies have been studied and found to be effective and/or comparable to conventional treatment, but some have been found to be ineffective or subject to conflicting and inconsistent results. Some CAM therapies have not been tested in definitive clinical trials. Factors that limit such research include the following:

  • Holistic, or whole system, modalities (eg, healthy diet pattern) encompass a large number of variables, many or all uncontrolled. In contrast, evidence-based medicine emphasizes one or a small number of variables, ideally controlled interventions (eg, drugs or procedures).

  • CAM therapies tend to be low cost and inadequately reimbursed, limiting financial incentive to fund research.

  • Regulation of CAM products and therapies does not require proven disease-specific efficacy.

The U.S. Food and Drug Administration (FDA), under the Dietary Supplement Health and Education Act (DSHEA) of 1994, allows marketing of dietary supplements and use of CAM devices but significantly restricts efficacy claims. Generally, manufacturers of dietary supplements can claim, without having to provide evidence for safety or efficacy to the FDA, benefit to the body’s structure or function (eg, improves cardiovascular health) but cannot claim benefit for treating disease (eg, treats hypertension). In 2019, the FDA announced its commitment to strengthening DSHEA and its regulation of dietary supplements.


Designing studies of CAM therapies poses challenges beyond those faced by researchers of conventional therapies:

  • Therapies may not be standardized. For example, there are different systems of acupuncture, and the contents and biologic activity of extracts made from the same plant species vary widely.

  • Diagnoses may not be standardized. Use of many CAM therapies (eg, traditional herbal medicine, homeopathy, acupuncture) is based on the patient’s unique characteristics or experiences rather than on a conventional medicine diagnosed disease or disorder.

  • CAM treatments may emphasize the whole person and thus include patients who may be excluded from evidence-based medicine randomized controlled trials because they have comorbidities.

  • Double- or single-blinding is often difficult or impossible. For example, patients cannot be blinded as to whether they are practicing meditation. Reiki practitioners cannot be blinded as to whether or not they are using energy healing.

  • Outcomes are difficult to standardize because they are often specific to the individual or focused on general health rather than based on objective and uniform measurements (as mean arterial pressure, HbA1C level, and mortality).

  • Placebos or control interventions may also be difficult to devise in complementary therapies. For example, in massage, the effective component could be touching, the specific area of the body massaged, the particular massage technique used, or time spent with the patient.

From a conventional research perspective, use of a placebo control is important. Placebo effect is complex, particularly when considering self-healing in the concept of care. CAM systems, however, recognize and interpret placebo effect as neurobiologic with mind-body implications, often with significant impact on symptoms and experience of disease (1 References Integrative medicine and health (IMH) and complementary and alternative medicine (CAM) include healing approaches and therapies that historically have not been included in conventional, mainstream... read more ).

In practice, CAM therapies are intended to enhance the quality of the healing environment and therapeutic relationships and thus optimize the patient’s capacity for healing. Studying the effective components of a CAM therapy against an inert placebo or control in a research setting remains a methodologic challenge.

Despite these challenges, many high-quality studies of CAM therapies (eg, acupuncture, homeopathy) have been designed and done. A systematic review has assessed many of the studies evaluating control acupuncture processes and devices (2 References Integrative medicine and health (IMH) and complementary and alternative medicine (CAM) include healing approaches and therapies that historically have not been included in conventional, mainstream... read more ). By using carefully designed placebos, researchers can isolate the effects of some CAM therapies on the overall clinical response. Evidence supporting the use of CAM includes some results that are more efficacious than placebo or non-inferior to conventional treatments. However, there is some high quality evidence for efficacy and safety of interventions that integrate CAM and conventional medicine treatments into IMH therapies (eg, dietary supplements paired to drugs that cause known deficiency, for example, vitamin B12 deficiency with long term use of metformin).


Although the safety of most CAM therapies has not been studied in clinical trials, many of these therapies have a good safety record. Many CAM therapies (eg, nontoxic botanicals, mind-body techniques such as meditation and yoga, body-based practices such as massage) have been used for thousands of years with scant evidence of harm, and many seem to have little potential for harm. However, there are some safety considerations, including the following:

  • Use of an alternative approach to treat a life-threatening disorder that can be effectively treated conventionally (eg, meningitis, cancer)—perhaps the greatest risk of alternative medicine, rather than the risk of direct harm from a specific therapy

  • Toxicity from certain botanical or supplement preparations (eg, hepatotoxicity from pyrrolizidine alkaloids, Atractylis gummifera, chaparral, germander, greater celandine, Jin Bu Huan, kava, pennyroyal, or others; nephrotoxicity from Aristolochia; adrenergic stimulation from ephedra)

  • Contamination (eg, heavy metal contamination of some Chinese and Ayurvedic herbal preparations; contamination of other products, such as PC-SPES and some Chinese herbs, with other drugs)

  • Interactions between CAM therapies (eg, botanicals, micronutrients, other dietary supplements) and other drugs (eg, induction of cytochrome P-450 [CYP3A4] enzymes by St. John’s wort, resulting in reduced activity of antiretrovirals, immunosuppressants, and other drugs), particularly when the drug has a narrow therapeutic index

  • As with any physical manipulation of the body (including mainstream techniques such as physical therapy), injury (eg, nerve or cord damage due to spinal manipulation in patients at risk, bruising in patients with bleeding disorders)

Current alerts about harmful dietary supplements are available at the FDA web site (Safety Alerts and Advisories). Historically, the FDA did not tightly regulate the production of dietary supplements, and some have been found to be diluted or contaminated. For example, a 2013 study found that 32% of botanical supplements (not limited to CAM supplements) did not contain the main active ingredient on the label, 20% contained contaminants (physiologically active compounds other than the ingredients desired or on the label), and another 21% contained fillers not listed on the label (3 References Integrative medicine and health (IMH) and complementary and alternative medicine (CAM) include healing approaches and therapies that historically have not been included in conventional, mainstream... read more ). However, new FDA regulations now require compliance with manufacturing practices that improve quality and safety of supplements, and high-quality products are available through certain manufacturers that comply with FDA Good Manufacturing Practices.

To help prevent injuries due to physical manipulations, patients should look for practitioners who are formally trained and professionally licensed. Rates of complications are very low when chiropractic or acupuncture is provided by practitioners with full credentials.


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Fortamet, Glucophage, Glucophage XR, Glumetza, Riomet, RIOMET ER
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