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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 a variety of healing approaches and therapies that historically have not been included in conventional Western medicine. Many aspects of CAM are rooted in ancient, indigenous systems of healing, such as those of China, India, Tibet, Africa, and the Americas.

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

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

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

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

Although the distinction between conventional medicine and IMH or CAM is not always easy to determine, a basic philosophical difference exists. Conventional medicine tends to base its practices on the best scientific evidence available. In contrast, CAM tends to base its practices on evidence-informed practices—evidence that may not necessarily 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 used by about 75% of Americans. They are the most common therapies included among integrative medicine and health (IMH) and complementary and alternative medicine (CAM)... read more , have been validated by the traditional high, strict scientific criteria.) Conventional medicine generally defines health as the absence of disease or dysfunction. The main causes of disease and dysfunction are usually considered to be identifiable factors, such as bacteria or viruses, biochemical imbalances, and aging, and treatments often involve drugs or surgery. In contrast, IMH and CAM practices often define health holistically, that is, as a balance of systems—physical, emotional, and spiritual—involving the whole person. Disharmony among these systems is thought to contribute to illness. Treatment involves strengthening the body’s own defenses and restoring these balances.


Acceptance and Use

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 addition, 57.6% of adults used at least one dietary supplement in the past 30 days.

Effectiveness and Safety

In 1992, the Office of Alternative Medicine within the National Institutes of Health (NIH) was formed to research the effectiveness and safety of alternative therapies. In 1998, this office became the National Center for Complementary and Alternative Medicine, and in 2015, it was renamed the National Center for Complementary and Integrative Health (NCCIH).


The effectiveness of alternative therapies is an important consideration.

Many CAM therapies have been studied and found to be ineffective or inconsistent. Some therapies have been shown to be effective for specific conditions. However, these therapies are often also used to treat other conditions and symptoms, even though scientific evidence is lacking for these uses, as is sometimes the case in conventional medicine. Some CAM therapies have not been tested in well-designed studies. However, a lack of evidence from well-designed studies is not proof that a therapy is ineffective.

Many CAM therapies are said to have been practiced for hundreds or thousands of years. They include acupuncture, meditation, yoga, therapeutic diets, massage, and botanical medicine. Having a long history of use is sometimes used as support that CAM therapies are effective. However, there are limitations with this argument:

  • Being used for a long time is not scientifically equivalent to proven effect. Some therapies subsequently found to be ineffective or harmful were previously used for many years.

  • The length of time a therapy has been in use is difficult to establish.

  • How a therapy was used in the past may differ from how it is used now, as may the therapy itself.

Thus, scientific evidence, using well-designed studies, is still preferred to determine whether a therapy is effective.

However, well-designed studies of CAM therapies can be difficult to do. Barriers to doing research on CAM therapies include the following:

  • Lack of support and financial resources for CAM among medical researchers

  • Limited training and skill to perform scientific research among advocates of CAM

  • Looser regulations requiring proof that CAM products or therapies are effective before they are made publicly available compared with regulations governing conventional medicine treatments

  • Generally lower financial returns for companies studying CAM than for those doing drug or device research

Applying conventional research methods to study CAM may be difficult for many additional reasons, including

  • The best conventional research design compares active treatment (such as a drug or treatment) with a placebo Placebos Placebos are substances that are made to resemble drugs but do not contain an active drug. (See also Overview of Drugs.) A placebo is made to look exactly like a real drug but is made of an... read more (an intervention that is made to resemble a drug or treatment but does not include an active drug or treatment) or no new intervention (a control group). For some CAM therapies, such as homeopathy and botanical medicine, designing a placebo is relatively easy. However, designing a placebo for physical treatments such as acupuncture or manual manipulation treatment is more difficult. Designing a placebo for meditation or whole system of healthy eating is even more of a challenge.

  • Separating the effects of a CAM therapy's active component from those of placebo is difficult. For example, CAM therapists typically interact with people in a positive and supportive way that is known to make people feel better, regardless of what other therapies are used. This aspect of CAM can be viewed as a placebo effect.

  • Conventional research design uses the method of double blinding. Double blinding involves preventing research subjects and practitioners from knowing which people were given which treatment. People and practitioners typically expect the active treatment to do better than the placebo. Double blinding reduces the likelihood that this expectation will bias the results in favor of the treatment. However, blinding practitioners may be difficult. For example, a Reiki practitioner would know whether a real energy treatment is being given. In such cases, the effectiveness of the treatment should be evaluated by a study investigator who does not know which treatment was used.

  • CAM therapies and diagnoses may not be standardized. For example, different practitioners use different systems of acupuncture, and the contents and effects of natural product preparations vary widely.

However, despite these challenges, many well-designed studies of CAM therapies (such as acupuncture and homeopathy) have been done. For example, one acupuncture study used a well-designed placebo, making double blinding possible, by placing an opaque sheath against the person's skin at an acupuncture point. Some sheaths contained a needle that penetrated the skin (active treatment), and some did not (placebo). For CAM therapies to be considered effective, there should be evidence that they are more effective when compared to a placebo or a control.

Lack of funding for well-designed CAM studies is often mentioned as a reason that these studies are not done. However, CAM products are a multi-billion dollar business, suggesting that lack of profitability should not be a reason companies do not study these products. However, profitability overall is much larger for conventional drug development than for CAM products.


Safety is another important consideration.

Did You Know...

  • Perhaps the greatest risk of complementary and alternative medicine (CAM) occurs when a person with a life-threatening disorder is treated with an unproven CAM therapy instead of a proven conventional medicine therapy.

The greatest health risk of CAM is likely

  • Use of an unproven therapy instead of a proven conventional therapy to treat a life-threatening disorder

Regarding the risk of CAM therapies themselves, some are clearly safe and even safer than conventional medicine practices. One key example is using meditation, acupuncture, and manual manipulation for pain management before or instead of opioid drugs. Other examples of safe practices include acupuncture to treat nausea, yoga to improve balance, or ginger tea to aid digestion. Others may conceivably be harmful. For example, because medicinal herbs and other dietary supplements (which are used in many alternative therapies) are not regulated as drugs by the US Food and Drug Administration (FDA), their safety is less certain than carefully regulated drugs (see Safety and Effectiveness Safety and Effectiveness Dietary supplements are used by about 75% of Americans. They are the most common therapies included among integrative medicine and health (IMH) and complementary and alternative medicine (CAM)... read more ).

Some general risks include the following:

  • Some substances in CAM preparations may interact dangerously with each other or with prescription drugs.

  • Highly purified dietary supplements are readily available in the United States and many countries in Europe, but products produced in other countries may contain dangerous contaminants, toxic ingredients, or other drugs.

  • Harm can be done by CAM therapies that involve manipulation of the body or other nonchemical interventions (for example, manipulation that injures vulnerable parts of the body).

In many cases of CAM, harm has neither been established nor excluded, but in some cases, potential harm has been shown. Sometimes the potential for harm is under-reported and under-appreciated by people who advocate use of the alternative products or therapies.

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Dramamine Motion Sickness Relief, Dramamine-N
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