The sciatic nerve is the largest nerve in the body, running from the lumbar and sacral plexuses, running from the back all the way down through the buttocks and thigh. Compression or inflammation at the base of the sciatic nerve is typically the primary cause of sciatica. Characteristic symptoms include a sharp electrical shooting pain down the leg, accompanied by numbness, tingling and sensitivity to touch.

The primary therapeutic goal is relief of the compression on the nerve.  You can relax the muscles and ligaments in the lower back directly with acupuncture or other forms of physical therapy. Chiropractic manipulation of the spine is also useful for restoring proper function to “locked-up” joints.

To construct a formula for treating sciatica, always use herbs that help relieve external spasm, such as kava root, valerian root and millettia stem. Also very useful is magnesium. Western-trained herbalists and TAM doctors both use lobelia
(L. pyramidalis) to treat sciatica, and this is the strongest treatment
in my experience. TCM doctors note that the combination of white peony root and licorice root in high doses for a short period of time is also useful for relieving the associated spasms.

In cases with more congestion, cold and restricted circulation, add herbs that open blockage like salvia root, prickly ash bark, tien chi root, liquidambar fruit (lu lu tong or L. taiwaniana), turmeric root, dang gui root, myrrh gum, cinnamon twig and ginger root. You can also make this formula as a tincture and apply it topically to the site of pain. A simple tincture combination of cayenne pepper and lobelia can be useful for both internal and external use, often affording quick relief (sold by Herb Pharm).
All of these herbs can also be made into a tea and soaked into a cotton cloth for direct warm application. In cases with more inflammation and heat, add herbs like bromelain, boswellia gum, phellodendron root, and scute root. It may be better to use cold applications here.  You will find that some of the TCM moving blood herbs mentioned are the basic ingredients in “secret” commercial applications sold at martial arts stores for treating athletic injury.