Ketamine, a dissociative anesthetic, appears promising as a treatment for complex regional pain syndrome. It may be used in low doses if other treatments have not worked. No benefit on either function or depression, however, has been seen.

Tentative evidence supports the use of bisphosphonates, calcitonin, and ketamine. Doing nerve blocks with guanethidine appears to be harmful. Evidence for sympathetic nerve blocks generally is insufficient to support their use. Intramuscular botulinum injections may benefit people with symptoms localized to one extremity.