Topical capsaicin versus diclofenac for chronic temporomandibular joint-related pain: a randomized, prospective, single-blind clinical trial

Chronic temporomandibular joint (TMJ)–related pain is a common condition associated with pain sensitization and functional limitation. Although topical capsaicin and diclofenac diethylammonium are used for musculoskeletal pain, direct comparative evidence in temporomandibular disorders is limited. This study aimed to compare their efficacy and safety in women with chronic TMJ-related pain. This randomized, prospective, single-blind clinical trial included 50 female patients aged 18–65 years with chronic temporomandibular joint (TMJ)-related pain. Participants were randomly assigned to receive either 0.075% topical capsaicin cream (Capciderm) or 1.16% topical diclofenac diethylammonium gel (Voltaren Emulgel), applied four times daily for 7 days. Sample size calculation showed that a minimum of 25 patients per group was required to achieve 80% power at a significance level of 0.05. Outcomes were assessed at baseline, day 8, and month 1 using the Visual Analog Scale (VAS), McGill–Melzack Pain Questionnaire, DN4 questionnaire, pressure pain threshold (PPT), maximum mouth opening, lateral mandibular excursions, clinical examination findings, Clinician Global Impression of Change (CGI), and adverse-effect monitoring. Greater short-term improvements were observed in the capsaicin group than in the diclofenac diethylammonium group across pain, sensory, and functional outcomes. McGill scores decreased from 64.20 ± 8.84 at baseline to 38.84 ± 10.77 on Day 8 and 35.96 ± 7.98 at Month 1 in the capsaicin group, compared with 59.00 ± 5.92, 59.00 ± 8.67, and 56.64 ± 10.55 in the diclofenac group. Repeated-measures analysis showed significant effects of time, group, and time × group interaction. VAS, DN4, and Facial Expressions Pain Scores also decreased more markedly in the capsaicin group. PPT values, maximum mouth opening, and lateral excursions improved significantly more with capsaicin. CGI improvement scores favored capsaicin at both follow-up points, while adverse-effect severity was low and comparable between groups. These findings should be interpreted as short-term between-group differences within an active-comparator adjunctive-treatment design. In women with chronic TMJ-related pain that persisted despite stabilization splint therapy, greater short-term improvements in pain and mandibular function were observed in the capsaicin group than in the diclofenac diethylammonium group. However, these findings should be interpreted as short-term between-group differences within an active-comparator adjunctive-treatment design; they do not establish the absolute treatment effect of capsaicin alone because the trial lacked a placebo, vehicle, or splint-only control arm and blinding may have been incomplete. Further placebo-controlled or vehicle-controlled trials with longer follow-up (at least 6 months), independent masked assessment, and standardized DC/TMD diagnostic classification are warranted. ClinicalTrials.gov Identifier: NCT07598994. Registered retrospectively on 19 May 2026.