One article on PainSci cites Derry 2014: Voltaren Gel: Does It Work?
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
BACKGROUND: Rubefacients containing salicylates cause irritation of the skin and are believed to relieve various musculoskeletal pains. They are available on prescription, and are common components in over-the-counter remedies. This is an update of a review of rubefacients for acute and chronic pain, originally published in 2009, which found limited evidence for efficacy. OBJECTIVES: To assess the efficacy and safety of topically applied salicylates in acute and chronic musculoskeletal pain in adults. SEARCH METHODS: We searched CENTRAL, MEDLINE, and EMBASE, from inception to 22 August 2014, together with the Oxford Pain Relief Database, two clinical trial registries, and the reference lists of included studies and relevant reviews. SELECTION CRITERIA: Randomised, double-blind, placebo- or active-controlled clinical trials of topical rubefacients containing salicylates to treat musculoskeletal pain in adults, with at least 10 participants per treatment arm, and reporting outcomes at close to 7 (minimum 3, maximum 10) days for acute conditions and 14 (minimum 7) days or longer for chronic conditions. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed trials for inclusion and risk of bias, and extracted data. We calculated risk ratio (RR) and number needed to treat to benefit or harm (NNT or NNH) with 95% confidence intervals (CI) using a fixed-effect model. We analysed acute and chronic conditions separately. MAIN RESULTS: New searches for this update identified one new study that satisfied our inclusion criteria, although it contributed information only for withdrawals. Six placebo- and one active-controlled studies (560 and 137 participants, respectively) in acute pain, and seven placebo- and three active-controlled studies (489 and 182 participants, respectively) in chronic pain were included in the review. All studies were potentially at risk of bias, and there were substantial differences between studies in terms of the participants (for example the level of baseline pain), the treatments (different salicylates combined with various other potentially active ingredients), and the methods (for example the outcomes reported). Not all of the studies contributed usable information for all of the outcomes sought.For the primary outcome of clinical success at seven days in acute conditions (mostly sprains, strains, and acute low back pain), the RR was 1.9 (95% CI 1.5 to 2.5) and the NNT was 3.2 (2.4 to 4.9) for salicylates compared with placebo, but this result was not robust (very low quality evidence). Using a random-effects model for analysis the RR was 2.7 (1.05 to 7.0). For the same outcome in chronic conditions (mostly osteoarthritis, bursitis, and chronic back pain), the RR was 1.6 (1.2 to 2.0) and the NNT was 6.2 (4.0 to 13) (very low quality evidence). This result was not substantially changed using a random-effects model for analysis. In both categories there were a number of factors might have influenced the results but sensitivity analysis was limited because of the small number of studies and participants.For both acute and chronic painful conditions any evidence of efficacy came from the older, smaller studies, while the larger, more recent studies showed no effect.Adverse events were more common with salicylate than with placebo but most of the events occurred in only two studies. There was no difference when these studies were removed from the analysis (very low quality evidence). Local adverse events (at the application site) were again more common with salicylate but were nearly all in one study (in which salicylate was combined with another irritant). There was no difference when this study was removed (very low quality evidence).There were insufficient data to draw conclusions against active controls. AUTHORS' CONCLUSIONS: The evidence does not support the use of topical rubefacients containing salicylates for acute injuries or chronic conditions. They seem to be relatively well tolerated in the short-term, based on limited data. The amount and quality of the available data mean that uncertainty remains about the effects of salicylate-containing rubefacients.
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Photobiomodulation therapy is not better than placebo in patients with chronic nonspecific low back pain: a randomised placebo-controlled trial. Guimarães 2021 Pain.
- No effect of creatine monohydrate supplementation on inflammatory and cartilage degradation biomarkers in individuals with knee osteoarthritis. Cornish 2018 Nutr Res.
- The CANBACK trial: a randomised, controlled clinical trial of oral cannabidiol for people presenting to the emergency department with acute low back pain. Bebee 2021 Med J Aust.
- Relationships Between Sleep Quality and Pain-Related Factors for People with Chronic Low Back Pain: Tests of Reciprocal and Time of Day Effects. Gerhart 2017 Ann Behav Med.
- Modulation in the elastic properties of gastrocnemius muscle heads in individuals with plantar fasciitis and its relationship with pain. Zhou 2020 Sci Rep.