|Acupuncture is the practice of inserting thin needles into specific body points to improve health and well-being. It originated in China more than 2,000 years ago. American practices of acupuncture use medical traditions from China, Japan, Korea and other countries. In the United States, the best-known type involves putting hair-thin, metallic needles in your skin. Research has shown that acupuncture reduces nausea and vomiting after surgery and chemotherapy. It can also relieve pain. Researchers don't fully understand how acupuncture works. It might aid the activity of your body's pain-killing chemicals. It also might affect how you release chemicals that regulate blood pressure and flow. Acupuncture is the stimulation of precisely defined, specific acupoints along the skin of the body involving various methods such as the application of heat, pressure, or laser, or penetration of thin needles. In a modern acupuncture session, an initial consultation is followed by taking the pulse on both arms, and an inspection of the tongue. Classically, in clinical practice, acupuncture is highly individualized and based on philosophy and intuition, and not on controlled scientific research. The number and frequency of acupuncture sessions vary but most practitioners don't think one session is sufficient. The application of evidence-based medicine to researching acupuncture's effectiveness is a controversial activity, which has produced different results in a growing evidence base of research. Some research results are encouraging but others suggest acupuncture's effects are mainly due to placebo. It is difficult to design research trials for acupuncture. Due to acupuncture's invasive nature, one of the major challenges in efficacy research is in the design of an appropriate placebo control group.