Multimodal analgesia with acetaminophen and/or nonsteroidal anti-inflammatory drugs is recommended for the treatment of postoperative pain. Although oral fixed-dose combinations (FDCs) are available, parenteral administration may be clinically justified. The goal of this study was to investigate the clinical efficacy and safety of an intravenous FDC of ibuprofen and acetaminophen after bunionectomy. This study was a prospective, randomized, double-blind, multicenter, placebo-controlled factorial clinical trial conducted at 2 clinical research centers in the United States between November 2016 and June 2017. Eligible patients (male and female subjects, aged 18-65 years, reporting pain intensity levels ≥40 mm on a 100-mm visual analog scale (VAS) after distal, first metatarsal bunionectomy) were randomized (3:3:3:2) to receive the FDC (ibuprofen 300 mg + acetaminophen 1000 mg), ibuprofen 300 mg, acetaminophen 1000 mg, or placebo (vehicle), administered as 15-minute intravenous infusions every 6 hours for 48 hours. The primary efficacy end point was the time-adjusted sum of pain intensity differences from baseline over 48 hours (SPID48). In addition to VAS pain intensity scores, pain relief scores, time to perceptible and meaningful pain relief, the use of rescue medication, and participant's global evaluations of the study drug were recorded. Adverse events occurring during the 48-hour treatment period were included in the safety analysis. A total of 276 participants were enrolled; most were female (82%), the mean age was 42.4 years, and the median baseline VAS was 67 mm, indicating moderate to severe pain. SPID48 was significantly higher for the FDC (23.4 [2.5] mm) than for ibuprofen (9.5 [2.5] mm), acetaminophen (10.4 [2.5] mm), and placebo (-1.3 [3.1] mm; all, P < 0.001). The superior analgesic effect of the FDC was supported by a range of secondary end points, including reduced opioid usage rates (75% for FDC, 92% for ibuprofen, 93% for acetaminophen, and 96% for placebo; all, P < 0.005). The safety profile of the FDC was comparable to that of intravenous ibuprofen or acetaminophen alone. Three participants withdrew from the study due to adverse events: 2 in the ibuprofen group and 1 in the acetaminophen group. The study found that repeated administration of an intravenous FDC of ibuprofen and acetaminophen provided statistically significant improvement in SPID48 over comparable doses of either monotherapy without an increase in adverse events. ClinicalTrials.gov identifier: NCT02689063. Copyright © 2019. Published by Elsevier Inc.