Seventy-six patients undergoing hand reconstructive surgery were randomized to receive Citrus aurantium (CA) essential-oil aromatherapy (n = 38) or placebo aroma (n = 38) in the early postoperative period in the ICU. All patients received standard care including IV paracetamol; the intervention group inhaled five drops of 30% CA essential oil on gauze held near the nose for one minute (active inhalation) followed by 30 minutes of passive exposure, whereas the control group received a visually and olfactorily matched placebo. The primary outcome was pain intensity measured with a numerical rating scale before the intervention, 30 minutes after, and one hour after the second measurement (≈90 minutes after start). Secondary outcomes included systolic and diastolic blood pressure at the same time points and adverse events. Outcomes were assessed from immediately prior to the intervention to approximately 90 minutes after initiation of aromatherapy. Overall, the results revealed significantly greater reductions in pain scores in the CA group versus placebo at 30 and 90 minutes (both p = 0.001), and CA exposure increased the odds of pain relief 1.73-fold in generalized estimating equation (GEE) analysis (Exp(B) = 1.73, p = 0.002). Systolic blood pressure declined more consistently over time with CA (Friedman p = 0.001; Exp(B) for SBP reduction = 16.78, p = 0.001), with no safety concerns or reported adverse effects, suggesting that CA aromatherapy is a simple, safe, and potentially useful adjunct to standard postoperative pain management in this setting.