Aim: The objective was to systematically review the efficacy and safety of topical
diclofenac in both acute and chronic
musculoskeletal pain in adults.Methods: We used standard Cochrane methods. Searches were conducted in MEDLINE, EMBASE and The Cochrane Register of Studies; date of the final search was November 2018. Included studies were randomized, double blinded, with ten or more participants per treatment arm. The primary outcome of "clinical success" was defined as participant-reported reduction in
pain of at least 50%. Details of adverse events (AEs) were recorded.Results: For
acute pain, 23 studies (5170 participants) were included. Compared to placebo, number needed to treat (NNT) for different formulations were as follows:
diclofenac plaster, 4.7 (95% CI 3.7-6.5);
diclofenac plaster with
heparin, 7.4 (95% CI 4.6-19); and
diclofenac Emulgel, 1.8 (95% CI 1.5-2.1). 4.1% (78/1919) reported a local AE. For
chronic pain, 21 studies (26 publications) with 5995 participants were included. Formulations included gel,
solution with or without
DMSO,
emulsion and plaster. A clinical success rate of ∼60% (NNT 9.5 [95% CI 7-14.7]) was achieved with a variety of formulations. Local AEs (∼14%) were similar for both
diclofenac and placebo.Conclusion: This systematic review of 11,000+ participants demonstrates that topical
diclofenac is effective for
acute pain, such as
sprains, with minimal AEs. The effectiveness of topical
diclofenac was also demonstrated in chronic
musculoskeletal pain but with a higher NNT (worse) compared with
acute pain. Formulation does play a part in effectiveness but needs further studies.