Coldness in the lower limbs due to lumbar disc herniation may be caused by the herniated lumbar disc compressing the dural sac, compressing the nerve root, or compressing both of the above at the same time. 1. Compression of the dural sac: the herniated lumbar disc compresses the dural sac, causing nerve damage and irritation, followed by abnormal skin temperature sensation and coldness in the lower limbs. 2. Compression of nerve root: when the protruding disc compresses the nerve root, the skin of the corresponding innervated area will feel abnormal. Not only is there pain and numbness in the skin, but also abnormal pain and temperature sensation in the skin, and the abnormal pain and temperature sensation will lead to coldness in the skin of the pressurized area. A herniated lumbar disc may also compress both of the above, and it is recommended that the patient seek timely treatment to avoid further aggravation of the condition.