The aim of our study was to explore the effect of local corticosteroids on dysphagia in patients undergoing anterior cervical discectomy and fusion (ACDF). To address a gap in the limited research on this topic, we utilized high-resolution impedance manometry (HRIM) and the Eating Assessment Tool-10 (EAT-10) questionnaire to assess the effects on key swallowing muscles, including the upper esophageal sphincter (UES). We randomly assigned patients undergoing ACDF to either the corticosteroid group or the saline solution group. Patients received 10 mg of local triamcinolone or saline solution prevertebrally at the cervical spine level before wound closure. Swallowing function preoperatively and at 1 month postoperatively were compared between the groups with use of HRIM parameters (e.g., UES relaxation, UES opening extent, intrabolus pressure, and pharyngeal contraction) and EAT-10 scores. Patients were also followed for postoperative complications and mortality within 12 months after surgery. Thirty patients completed the study. The median age was 55 years in the corticosteroid group and 57 years in the saline group, and each group had 8 female patients. All participants were Taiwanese. We found no significant difference in median preoperative UES relaxation pressure between the corticosteroid and saline solution groups (33.8 and 31.3 mm Hg, respectively; p = 0.54). Postoperatively, the corticosteroid group had significantly lower median UES relaxation pressure than the saline solution group (24.5 versus 33.6 mm Hg; p = 0.01). Before and after surgery, all other HRIM parameters and EAT-10 scores were similar between the groups, with the corticosteroid group demonstrating median pre- and postoperative EAT-10 scores of 0 and 4, respectively, and the saline solution group demonstrating scores of 2 and 3, respectively. There were no adverse events. The findings suggest that local corticosteroids may reduce UES relaxation pressure at 1 month after ACDF, potentially enhancing UES opening. Further research is required to verify our findings. Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.