In Traditional Chinese Medicine (TCM), multiple sclerosis is associated with a Wei or flaccidity syndrome, which results in muscular weakness. This is an association, not a classification, however-Wei syndromes generally do not result in pain and some symptoms of MS may be painful. Aspects of MS are associated with Bi or blockage syndrome as well.

Like Wei syndrome, however, TCM theorizes the origin of MS to be an invasion of External Pathogenic Factors such as Dampness (which affects the Spleen and muscles) in patients with a weak Spleen Zang, or a deficiency in the Liver and Kidney Zang (which affects the tendons and bones, and are thought to play a role in the function of the nervous system. Hence, the etiology of MS may be varied and include factors such as early exposure to damp environments, improper diet, excessive sexual activity, shock, and a predisposition towards Liver and Kidney Zang deficiency. The initial stages of MS usually result from Dampness invading the muscles. As the disease progresses, symptoms of Liver and Kidney Zang Deficiency frequently begin to develop and may progress to symptoms of Liver Yang rising, such as dizziness or stiffness, and then to Liver Wind, resulting in tremors and paralysis.