It is unknown if the blood pressure-lowering effects of loop diuretics are due solely to their diuretic effect and data on dose-related decreases in systolic and/or diastolic blood pressure (BP) among drugs in this class are scarce. A review in the Cochrane Library identified nine randomized controlled trials (RCTs) to determine dose-related decreases in systolic and/or diastolic BP among loop diuretics, along with dose-related adverse events.

All nine studies were double-blind placebo-controlled trials with follow-up duration of at least three weeks and a total of 460 participants (mean age of 54.4, mean duration of 8.8 weeks at a fixed dose of loop diuretics, weighted mean baseline BP of 162/103 mmHg). The studies included loop diuretic monotherapy with furosemide, bumetanide, piretanide, torsemide, azosemide, ethacrynic acid, tripamide, phenoxybenzoic acid, muzolimine, indacrinone, etozolin, ozolinone, cicletanine, tienilic acid (ticrynafen), and tizolemide.

There was low-quality evidence on the overall systolic and diastolic BP-lowering efficacy of loop diuretics; the effect was modest at -8/-4mmHg vs. placebo but this number is likely to be overestimated. The BP-lowering effect did not differ significantly from thiazides, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, or renin inhibitors. There was insufficient evidence to assess the BP-lowering differences between the loop diuretics and to evaluate dose equivalence between these drugs. However, given that the mechanism of action of these drugs is similar, the authors note that it is likely that the effect on BP with these various loop diuretics at equivalent doses is the same. Due to the short duration of the studies and lack of reporting on adverse events, no estimates on incidence of harms could be included.