There are two causes of pain in the lateral side of the leg: 1, the pain in the lateral thigh is mostly seen in lateral femoral cutaneous neuritis, also called lateral femoral cutaneous nerve entrapment syndrome, which is the inflammation of the lateral femoral cutaneous nerve in the iliac crest area by the entrapment of the nerve when it exits the pelvis, so it manifests as tingling, numbness, hot fever and so on in the skin of the lateral thigh. 2, the pain in the lateral calf is mostly due to lumbar 4-5 The herniated disc compresses the lumbar 5 nerve. Because the lateral calf is innervated by the lumbar 5 nerve, numbness and pain will occur after the nerve is compressed, and the edema and inflammation of the nerve root area will make the pain worse. Chinese medicine believes that most of the pain on the lateral side of the leg is caused by wind-cold and dampness in the foot Shaoyang gallbladder meridian, as well as qi-blood stagnation and phlegm-stasis obstruction.