ObjectiveTo determine whether dexketoprofen administered by phonophoresis or iontophoresis is more effective for the treatment of subacromial impingement syndrome (SIS) than conventional ultrasound therapy. DesignRandomised clinical trial. SettingUniversity hospital. ParticipantsNinety-nine participants with SIS without a complete tear of the rotator cuff were assigned at random to three intervention groups. Intervention groupsParticipants received ultrasound (n=32), phonophoresis with dexketoprofen (50mg/session) (n=33) or iontophoresis with dexketoprofen (50mg/session) (n=34). All participants completed 20 treatment sessions plus exercise therapy and cryotherapy. Outcome measuresA visual analogue scale (VAS), the Constant–Murley Scale (CMS) and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire were administered pre-treatment (baseline), post-treatment and 1 month post-treatment. ResultsAt baseline, there were no differences between the groups. Post-treatment, VAS score improved by −1.2 points and CMS score improved by 8.9 points in the ultrasound group compared with the iontophoresis group [95% confidence interval (CI) −0.2 to −2.2 and 95% CI 17.0 to 0.7, respectively]. CMS score improved by 7.1 points in the phonophoresis group compared with the iontophoresis group (95% CI 14.8 to −0.7). At 1 month post-treatment, no significant differences were detected between the groups. VAS, CMS and DASH scores of all groups improved post-treatment and at 1 month post-treatment. ConclusionUltrasound, iontophoresis with dexketoprofen and phonophoresis with dexketoprofen can improve pain, shoulder function, and physical functioning and symptoms in the upper limb in patients with SIS without a complete tear of the rotator cuff. Clinical Trials.gov registration numberNCT01748188.