Background and Objective: A supraclavicular brachial plexus block (SCBPB) is a safe alternative to general anesthesia in upper limb surgeries. We compared the effect of adding magnesium sulfate (MS) and low-dose dexamethasone (LDD) to ropivacaine in SCBPB in elective upper limb surgeries. 
Materials & Methods: The ultrasound-guided SCBPB was done on 55 candidates for elective upper extremity surgeries in 3 groups by using 200 mg MS + 24 mL ropivacaine 0.5% (MS Group), 4 mg dexamethasone + 24 mL ropivacaine 0.5% (LDD Group), and 1 mL normal saline + 24 mL ropivacaine 0.5% (NS Group). The sample was investigated for the sensory and motor block onset, motor and sensory block duration, analgesia duration, total opioid consumption, and the Visual Analog Scale (VAS) during sensory return.
Results: The onset of motor and sensory block was faster in the MS group compared to the LDD and NS group (P<0.05). The sensory block duration was longer in the LDD group compared to the MS and NS groups. The duration of motor block and analgesia in the LDD group was significantly longer than the NS group (P<0.05). However, this difference was not significant regarding the MS group (p>0.05). The LDD and MS groups were not different in terms of total opioid consumption and VAS at the time of sensory return. However, both groups had significant differences with the NS group (P<0.05).
Conclusion: The LDD prolonged the motor and sensory block duration and analgesia compared to MS.