Intranasal fentanyl (INF) quickly and noninvasively relieves severe pain, whereas intravenous hydromorphone (IVH) reliably treats severe cancer pain but requires vascular access. The trial evaluated the efficacy of INF relative to IVH for treating cancer patients with severe pain in an emergency department (ED) setting. Methods We randomized 82 patients from a comprehensive cancer center ED to receive INF (n = 42) or IVH (n = 40). Eligible patients reported severe pain at randomization (�7, scale: 0 "none" to 10 "worst pain"). We conducted non-inferiority comparisons (non-inferiority margin = 0.9) of pain change from treatment initiation (T0) to one hour later (T60). T0 pain ratings were unavailable; therefore, we estimated T0 pain by comparing 1) T60 ratings, assuming similar group T0 ratings; 2) pain change, estimating T0 pain = randomization ratings, and 3) pain change, with T0 pain = 10 (IVH group) or T0 pain = randomization rating (INF group). Results At T60, the upper 90% confidence limit (CL) of the mean log-transformed pain ratings for the INF group exceeded the mean IVH group rating by 0.16 points (>pain). Substituting randomization ratings for T0 pain, the lower 90% CL of mean pain change in the INF group extended 0.32 points below (