Capsaicin can be used to help treat rheumatoid arthritis due to its mild side effects, according to a Cochrane review.
Researchers found only 10 trials, involving around 300 patients, on the use of muscle relaxants and neuromodulators for managing rheumatoid arthritis pain.
Their review found no evidence that muscle relaxants were better than placebo at reducing pain and only weak evidence to support neuromodulators such as oral nefopam, topical capsaicin and oromucosal cannabis. But they said the mild adverse events linked with capsaicin meant it could be considered as an “add-on therapy” for persistent local pain.
When looking at muscle relaxants, they found neither the benzodiazepine agents, diazepam and triazolam, nor the non-benzodiazepine agent, zopiclone, reduced pain when taken for one to 14 days. However, even this short use was associated for both agents with drowsiness and dizziness.
When looking at neuromodulators, the researchers found weak evidence that using oral nefopam, topical capsaicin and oromucosal cannabis for one to seven days can reduce pain in patients with rheumatoid arthritis better than placebo.
Lead author Bethan Richards, from the Institute of Rheumatology and Orthopedics at Melbourne’s Royal Prince Alfred Hospital, said: “Until further research is available, given the relatively mild nature of the adverse events, capsaicin could be considered as an add-on therapy for patients with persistent local pain and inadequate response or intolerance to other treatments.
“However, oral nefopam and oromucosal cannabis have more significant side effect profiles and the potential harms seem to outweigh any modest benefit achieved,” she added.