Erythromelalgia is a rare syndrome characterized by pain, redness, and heat involving the lower and, less frequently, the upper extremities. Symptoms occur with local or environmental stimulation and may be mild for years or become disablingly severe. A finding of relief with ice-water immersion helps distinguish erythromelalgia from disorders such as causalgia and reflex sympathetic dystrophy. Erythromelalgia may be classified in three ways: (1) early-onset, (2) adult-onset aspirin-sensitive, and (3) adult-onset non-aspirin-sensitive. Treatment options, which include medication, sympathetic blocks, and surgery, are determined by classification.