This single-centre, randomized, double-blind, placebo-controlled phase II trial evaluated whether intravenous salbutamol provides additional analgesia for emergency department (ED) patients with suspected renal colic. Of 151 consented participants, 108 with imaging-confirmed renal colic comprised the modified intention-to-treat population for the primary outcome. Participants were randomized 1:1 to receive a 250 µg slow intravenous bolus of salbutamol or placebo, each given alongside standard ED analgesic care. The primary endpoint was the between-group difference in 30-minute change in 100-mm Visual Analogue Scale (VAS) pain score, with a prespecified minimal clinically important difference (MCID) of 13 mm. Salbutamol produced no statistically or clinically significant additional analgesia compared with placebo. Median VAS pain reduction at 30 minutes was 18 mm (IQR −25 to −3) with salbutamol versus 13 mm (IQR −33 to −1) with placebo. The between-group difference was 5 mm (95% CI −16 to 6; p = 0.575). Secondary endpoints, including opioid consumption, patient satisfaction, and qualitative pain measures, showed no meaningful between-group differences. Adverse events were more frequent with salbutamol (69% vs 47%), most commonly tremor, palpitations, and dizziness.