As of 2013 low quality evidence supports the use of bisphosphonates. A 2009 review found "very limited data reviewed showed that bisphosphonates have the potential to reduce pain associated with bone loss in patients with CRPS I, however, at present there is not sufficient evidence to recommend their use in practice".

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.