Systematic review of topical capsaicin for the treatment of chronic pain.
OBJECTIVE
To determine the efficacy and safety of topically applied capsaicin for chronic pain from neuropathic or musculoskeletal disorders.


METHODS
Cochrane Library, Medline, Embase, PubMed, an in-house database, and contact with manufacturers of topical capsaicin.


METHODS
Randomised controlled trials comparing topically applied capsaicin with placebo or another treatment in adults with chronic pain.


METHODS
Primary outcome was dichotomous information for the number of patients with about a 50% reduction in pain. Outcomes were extracted at four weeks for musculoskeletal conditions and eight weeks for neuropathic conditions. Secondary outcomes were adverse events and withdrawals due to adverse events.


RESULTS
Six double blind placebo controlled trials (656 patients) were pooled for analysis of neuropathic conditions. The relative benefit from topical capsaicin 0.075% compared with placebo was 1.4 (95% confidence interval 1.2 to 1.7) and the number needed to treat was 5.7 (4.0 to 10.0). Three double blind placebo controlled trials (368 patients) were pooled for analysis of musculoskeletal conditions. The relative benefit from topical capsaicin 0.025% or plaster compared with placebo was 1.5 (1.1 to 2.0) and the number needed to treat was 8.1 (4.6 to 34). Around one third of patients experienced local adverse events with capsaicin, which would not have been the case with placebo.


CONCLUSIONS
Although topically applied capsaicin has moderate to poor efficacy in the treatment of chronic musculoskeletal or neuropathic pain, it may be useful as an adjunct or sole therapy for a small number of patients who are unresponsive to, or intolerant of, other treatments.
Mason
Lorna
L
Pain Research and Nuffield Department of Anaesthetics, University of Oxford, Oxford Radcliffe Hospital, Headington, Oxford OX3 7LJ.
Moore
R Andrew
RA
Derry
Sheena
S
Edwards
Jayne E
JE
McQuay
Henry J
HJ
D000287:Administration, Topical; D000700:Analgesics / Q000008:administration & dosage* / Q000009:adverse effects; D002211:Capsaicin / Q000008:administration & dosage* / Q000009:adverse effects; D002908:Chronic Disease; D006801:Humans; D009140:Musculoskeletal Diseases / Q000150:complications; D009437:Neuralgia / Q000188:drug therapy; D010146:Pain / Q000188:drug therapy* / Q000209:etiology; D010147:Pain Measurement; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome
D000700:Analgesics; D002211:Capsaicin