Background: Evidence for modulating the sodium chloride (NaCl) intake of patients hospitalized with acute heart failure (AHF) is inconclusive. Salt restriction may not benefit; hypertonic saline may aid diuresis., Objective: To compare the safety and efficacy of oral NaCl during intravenous (IV) diuretic therapy in renal function and weight., Methods: Seventy hospitalized patients with AHF who were being treated with IV furosemide infusion consented to receive, randomly, 2 grams of oral NaCl or placebo 3 times a day in a double-blind manner during diuresis. Treatment efficacy (bivariate primary endpoints of change in serum creatinine levels and change in weight) was measured at 96 hours, and adverse safety events were tracked for 90 days., Results: Sixty-five patients (34 NaCl, 31 placebo) were included for analysis after 5 withdrew. A median of 13 grams of NaCl was given compared to placebo. At 96 hours, there was no significant difference between treatment groups with respect to the primary endpoint (P = 0.33); however, the trial was underpowered, and there was greater than expected standard deviation in weight change. The mean change in creatinine levels and weight was 0.15 ± 0.44 mg/dL and 4.6 ± 4.2 kg in the placebo group compared with 0.04 ± 0.40 mg/dL and 4.0 ± 4.3 kg in the NaCl group (P = 0.30 and 0.57, respectively). Across efficacy and safety endpoints, we observed no significant difference between the 2 groups other than changes in serum sodium levels (-2.6 ± 2.7 in the placebo group and -0.3 ± 3.3 mEq/L in the NaCl group; P < 0.001) and in serum blood urea nitrogen levels (11 ± 15 in the placebo group; 3.1 ± 13 mEq/L in the NaCl group; P = 0.025)., Conclusions: In this single-center study, liberal vs restrictive oral sodium chloride intake strategies did not impact the safety and efficacy of intravenous diuretic therapy in patients with AHF. (ClinicalTrials.gov registration NCT04334668.)., Competing Interests: Disclosures TM receives grant support from Ionis Therapeutics unrelated to this work, serves as an advisor to Recora Health and Cleveland Clinic American Well Joint Venture, and he or his institution has received fees as part of serving on advisory boards for AstraZeneca, Abbott, Bayer, Boehringer-Ingelheim, Daiichi Sankyo, Novartis, Novo Nordisk, and Vifor and is supported by a grant from the Belgian American Educational Foundation and the Frans Van de Werf Fund. JDE is a consultant for Abbott, Getinge and BioVentrix. WHWT is a consultant for Sequana Medical, Cardiol Therapeutics, Genomics plc, Zehna Therapeutics, Renovacor, Boston Scientific, Kiniksa, WhiteSwell, and CardiaTec Biosciences and has received honoraria from Springer Nature and the American Board of Internal Medicine. All other authors have no relationships to disclose., (Copyright © 2023 Elsevier Inc. All rights reserved.)