Objectives: This study aimed to evaluate the efficacy and postoperative complications of preoperative submucosal dexamethasone injection compared to preoperative dexamethasone injection into the pterygomandibular space for surgical extraction of the impacted lower third molar. Study design and setting: This was a quasi-experimental, cross-sectional study conducted at the Department of Oral and Maxillofacial Surgery, Dow International Dental College, Dow University of Health Sciences, Karachi, from April to July 2021. Methodology: The study sample consisted of 72 patients who reported surgical extraction of their lower wisdom teeth and consented to participate in this study. The patients were randomly divided into the submucosal injection group (SM) and the pterygomandibular space (PM) group. The injection time was recorded on the second and seventh postoperative days. Results: No significant differences in the duration of the intervention were observed between the two groups (23.08 min in PM, 23.07 min in SM). The postoperative facial swelling was significantly reduced transversely (ear lobe to the angle of the mouth) in both groups compared to their respective baselines on the first postoperative day. On the secondpostoperative day, significant changes were observed in the submucosal group in postoperative swelling. Conclusions: Using intraoral dexamethasone injections in third molar surgery significantly reduces conventional complications of surgery while avoiding the systemic side effects of steroids. Dexamethasone should be used regardless of the administration site when warranted, with less apprehension than is common in dentistry