According to TCM, patients who present sciatic pain are usually diagnosed as suffering from a type of bi syndrome. Bi syndromes involve blockage and pain and are especially prevalent in the lower half of the body. Bi syndromes are often caused by unknown factors; that is, there may be little apparent reason for the occurrence, though a significant injury to the back would be an obvious cause. From the period of the Neijing to the present, bi syndrome has been said to be induced mainly by the influences of cold, damp, and wind.  Because of the location in the lower body, and the tendency of the pain to radiate downwards, the disorder is frequently attributed to a combination of cold and dampness: these are yin factors that have a natural downward course. Wind, an external pathogenic factor of mysterious nature is thought to carry the pathogenic influences into the body and contribute to the variable nature of the pain.

Internally, a deficiency of kidney yang can give rise to cold and damp syndromes affecting the lower body. In this case, external wind may not be a factor in causing the pain, though it can still combine with cold and dampness to exacerbate the underlying condition. Chinese herbal therapies for sciatica and lumbago usually involve warming the kidney yang, dispelling chill, clearing dampness, and resolving wind-cold-damp complexes.

Sciatica is relatively rarely mentioned in the Chinese medical literature. Low back pain is frequently addressed in a cursory manner, with standard differential diagnosis of syndromes such as kidney yang deficiency, kidney yin deficiency, wind-cold-damp syndrome, blood stasis, and damp-heat accumulation. Kidney deficiency and wind-cold-damp syndromes dominate the discussions, as reflected in the formulas below. Blood-stasis syndrome is usually discussed only in relation to obvious severe traumatic injury, and damp-heat accumulation is considered a rare causative factor. 

It was our report that wind-cold-dampness was the prominent factor in 43% of cases, deficiency of kidney was prominent in 22% of cases, and sprain (physical injury) accounted for 22% of cases. In a similar report involving 106 cases of sciatica, 50 cases were attributed to cold, damp, and wind invasion, 49 cases to acute lumbar strain, and 7 cases due to internal cold (kidney yang deficiency). Acute sprain is most often treated by acupuncture, whereas chronic cases, especially those due to the other causative factors, are treated mainly by herbal prescriptions.