Myofascial pain syndrome (MPS) originates in the muscle and fascia. MPS presents with referred pain specific for each muscle and a trigger point that reproduces the symptoms. Trigger-point-injection (TPI) is an effective approach to treating MPS. Some TPI agents, however, are associated with systemic and local side effects.

The aim of this study was to evaluate the effectiveness of TPI with a conventional active drug mixture (CADM) vs. that with normal saline solution (NS) alone in patients with MPS presenting to the emergency department (ED).

Adults with MPS diagnosed in the ED, participants were randomly assigned to receive TPI with NS or with CADM. Pain intensity was scored using a 0–10 numeric rating scale prior to and after TPI, before discharge and 2 weeks after TPI.

Among 48 patients analyzed, 23 received TPI with NS. The mean pain scores were as follows: immediately before TPI, 7.59 (NS) and 7.44 (CADM); immediately after TPI, 2.22 (NS) and 1.76 (CADM); prior to discharge, 1.52 (NS) and 1.76 (CADM). At 2-week follow up, the mean pain scores were 4.29 (NS) and 4.14 (CADM). Pain was significantly reduced after TPI in both groups. At 2 weeks, the mean pain scores were similar between the groups. No adverse events were reported.

In cases of MPS in the ED, pain can be controlled with TPI independent of the injectate. TPI with NS may be preferred over CADM because of its lower cost and more favorable side effect profile.