Sciatica with cold leg on one side may be caused by nerve entrapment, local blood flow obstruction and so on. 1. Nerve compression: sciatica is caused by the sciatic nerve compression and the corresponding symptoms. It may cause neurosensory dysfunction and a feeling of coldness in the area along the sciatic nerve, but the surface temperature of the skin is generally not abnormal. 2. Local blood transportation obstacle: long-term compression of the sciatic nerve may cause local muscle vascular constriction, narrowing or spasm, resulting in a relative slowing down or reduction of local blood transportation, which may affect the blood circulation of the affected side of the limb and the distal end, resulting in ischemia, hypoxia, and coldness on the affected side of the limb. If one side of the leg is cold, it is recommended to consult a doctor as soon as possible to make a clear diagnosis and carry out standardized treatment in order to reduce the adverse effects of the disease.