A resurgence of interest developed in the 1990s in medical treatments not fully accepted by conventional medicine or biomedicine, which requires stringent scientific proof of safety and effectiveness before accepting a treatment. Such evidence is lacking for many approaches used in the medical systems and treatments known as alternative medicine in the United States. In Europe, these same approaches often are called complementary medicine. Growing public interest in nontraditional treatments led the NIH to open the National Center for Complementary and Alternative Medicine (formerly the Office of Alternative Medicine) in 1992, which encourages research on alternative medicine. The number of Americans using an alternative therapy rose from 33 percent in 1990 to more than 42 percent in 1997.

Alternative medicine emphasizes improving the quality of life for people with chronic illness; disease prevention; and treatments for conditions that conventional medicine cannot adequately control, such as arthritis, chronic pain, allergies, cancer, heart disease, and depression. A cornerstone of alternative medicine is the idea that the mind influences the health of the body.

Alternative medical systems include chiropractic, holistic medicine, and homeopathy. Chiropractors treat disease with spinal manipulation, massage, diet, and many other techniques. Holistic healers emphasize treatment of the whole person, including body, mind, emotions, spirit, and interactions with the family and environment. Homeopathic healers use substances that cause the very symptoms being treated. When treating a headache or nausea, for example, homeopathic healers administer herbs that in large doses cause headache or nausea. But they use very small doses that cause the patient no discomfort.

Specific alternative medical treatments include aromatherapy, inhaling oils from aromatic plants; massage techniques, including Rolfing and reflexology; biofeedback; iridology, in which the eye is used to diagnose certain diseases; and acupuncture. Some approaches, including chiropractic manipulation and acupuncture, have gained greater acceptance in conventional medicine. Some conventional biomedical studies have concluded that chiropractic manipulation is effective for low-back pain. A 1997 NIH report gave acupuncture limited endorsement for certain medical uses.

Organizations that educate the public about health fraud and quackery expressed concern about growing interest in some alternative medicine treatments. They emphasized the importance of receiving a conventional medical diagnosis, and exploring standard treatment options, before turning to alternative medicine.