Reflex sympathetic dystrophy syndrome is a chronic condition associated with severe burning pain, pathological changes in bone and skin, tissue swelling, excessive sweating and extreme sensitivity to touch. It occurs especially after injuries from high-velocity impacts such as those from bullets. However, it may occur without apparent injury. One visible sign of R.S.D near the site of injury is warm, shiny red skin that later becomes cool and bluish. The pain is out of proportion to the severity of the injury and gets worse over time. Eventually the joints become stiff from disuse, and the skin, muscles, and bone atrophy. The symptoms of R.S.D vary depending on the severity and duration.

The cause of R.S.D is unknown and it is treated with a variety of drugs. A good prognosis of R.S.D. can usually be made if it is detected within the first three months of the symptoms.