The Chinese believed that Qi is an energy source that flows through your body in channels. Qi is the source and cause of all movement, voluntary and involuntary (Stux and Pomeranz 75). It protects the body from external dangers that could lead to illness. Protective Wei Qi mostly found at the surface of the skin.
According to the Chinese theory, most illnesses are a disturbance of the flow of Qi in the body (Stux and Pomeranz 76). A disturbance can be an excess Qi or a lack of Qi. A blockage of Qi in the channels and organs can be another cause of sickness.
When the flow of Qi is disturbed, the most prominent symptom is pain (Stux and Pomeranz 77). This is because, without Qi, you cannot function normally. Everything is directed by Qi, even mental activity and body heat.
An excess of energy leads to the organ systems overworking (Stux and Pomeranz 76). These are known as Shi or Yang conditions. Symptoms are inner uneasiness, cramp-type pain, and overexcitement.
When there isn't enough QI in the body (deficiency), these conditions are known as a weakness in the Qi, causing the organs to malfunction. The Chinese named these conditions "Xu conditions". Some symptoms include being cold, low blood pressure, and general weakness. Illness that can be the result of this are of the degenerative kind, like old age or depression.
When the needle is inserted, patients feel a sensation called Dei Qi by the Chinese. Which can be described as feeling numb, cold, hot, or sore. The sensation is never felt in the exact same place for each patient, and it can also depend on where the needle was inserted. Often the sensation has been described as traveling along a channel (Stux and Pomeranz 204).
Even though many western doctors and scientists doubted using acupuncture as a pain-relieving method, today acupuncture is used more widely around the world. It is estimated that over a million practioners use acupuncture outside of China. (Stux and Pomeranz 2). Arguably, the most important step for use of acupuncture outside of China was in 1996, when the Us Food and Drugs Administration (FDA) decided to reclassify acupuncture. Before, the FDA had put acupuncture in Class three (Class 1 being safe and effective, Class 2 being safe and effective but needing special labeling with instructions, Class 3 being devices that require investigation). In Class 3, it could only be used for research purposes, like a hospital lab. In 1996, the FDA moved the needle to Class 2, meaning it can be used, but only by those liscensed, and with special care (Stux and Pomeranz 3).