Erythromelalgia (erythros red melos extremity algos pain) is a peripheral vasodilatory dysfunction of unknown origin. Primary erythromelalgia: the cause is unknown and may be related to autonomic nervous system dysfunction. Secondary erythematous limb pain: 1. drugs: metronidazole, ampicillin, calcium antagonists, vasoactive drugs; 2. secondary to other diseases: such as diabetes, SLE, rheumatoid arthritis, gout, multiple sclerosis, infectious mononucleosis, etc. 3, concomitant or combined: peroneal muscular dystrophy with erythematous limb pain, pulmonary heart disease with erythematous limb pain, erythematous limb pain with chronic osteomyelitis, erythematous limb pain with leukocytoclastic vasculitis, erythematous limb pain associated with genetic sensory neuropathy, and erythematous limb pain associated with paraneoplasia. Typical symptoms: redness, warmth and burning pain in the extremities, with lightness during the day and heaviness at night. The extremity may have objective sensory loss, thickened finger (toe) nails, muscle atrophy, and long duration of the disease may have ulcers and gangrene. Treatment: 1, maintain rest: acute rest in bed, elevate the affected limb. Chronic period is not easy to apply cold water for a long time, should be the main insulation. 2, drugs: vasodilators, aspirin, reserpine, glutathione, B vitamins, gabapentin, carbamazepine, pregabalin, glucocorticoids, cycloheximide, sodium nitroprusside. 3.Nerve block therapy: sacral canal therapy, epidural placement therapy 4.Minimally invasive interventional therapy: sympathetic ganglion disruption before treatment: after treatment.