A 15-year-old female complained of reddening, edema, and pain in her hands and feet. The symptoms were relieved upon cooling. From these findings, a diagnosis of erythromelalgia was made. Because none of the oral medication prescribed by dermatologist was effective, the patient was consulted to our department. A low dose of ketamine, a drug considered to be effective for intractable pain, was administered intravenously and the pain subsided significantly. Furthermore, the pain became completely controllable with a combination of intramuscular ketamine injection and other oral medication.