• Lorna Mason, R Andrew Moore, Sheena Derry, Jayne E Edwards, and Henry J McQuay.
• Pain Research and Nuffield Department of Anaesthetics, University of Oxford, Oxford Radcliffe Hospital, Headington, Oxford OX3 7LJ.
• BMJ. 2004 Apr 24;328(7446):991.

ObjectiveTo determine the efficacy and safety of topically applied capsaicin for chronic pain from neuropathic or musculoskeletal disorders.Data SourcesCochrane Library, Medline, Embase, PubMed, an in-house database, and contact with manufacturers of topical capsaicin.Study SelectionRandomised controlled trials comparing topically applied capsaicin with placebo or another treatment in adults with chronic pain.Data ExtractionPrimary 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.Data SynthesisSix 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.ConclusionsAlthough 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.

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