Patients with CRPS I and II will receive an individualized regimen of physical therapy and standard treatment to control their pain. In addition, they will receive neurotropin or placebo tablets for 5 weeks, then no trial medicine for at least 1 week, and then the other trial drug for the next 5 weeks. That is, patients who took placebo the first 5 weeks will take neurotropin the second 5 weeks and vice versa. Neither the patients nor the doctors will know who received which drug during the two intervals until the study is over. Patients will complete questionnaires about their pain, quality of life, and ability to perform daily living activities. They will have various tests to measure pain (such as sensitivity to heat and cold, to an electric current, to a mild pin prick, etc.); to provide information about changes in their condition (such as tests of range of motion of joints and limb size); to measure blood circulation and sweating in the arm or leg (such as measurements of blood flow to the limb, skin temperature, and sweat production), and other procedures.