Synephrine has been used to promote
weight loss; however, its safety and efficacy have not been fully established. The goals of our study were to give an overview of the safety and efficacy of p-
synephrine, to systematically evaluate its efficacy regarding
weight loss and to assess its safety, focusing on its cardiovascular side effects in a meta-analysis. PubMed, the Cochrane Library, Web of Science and Embase were searched for relevant studies. Only placebo-controlled, human clinical trials with
synephrine intervention were included in the meta-analysis. The meta-analysis was reported according to the
PRISMA guidelines using the PICOS format and taking into account the CONSORT recommendations. Altogether, 18 articles were included in the meta-analysis. Both systolic and diastolic blood pressure (DBP) increased significantly after prolonged use (6.37 mmHg, 95% CI: 1.02-11.72, p = 0.02 and 4.33 mmHg, 95% CI: 0.48-8.18, p = 0.03, respectively). The
weight loss in the
synephrine group was non-significant after prolonged treatment, and it did not influence body composition parameters. Based on the analyzed clinical studies,
synephrine tends to raise blood pressure and heart rate, and there is no evidence that
synephrine can facilitate
weight loss. Further studies are needed to confirm evidence of its safety and efficacy.