Background: Although artificial and non-nutritive sweeteners are widely used and “generally recognized as safe” (GRAS) by US and EU regulatory agencies, there have been no clinical trials to assess either long-term cardiovascular disease (CVD) risks or short-term CVD-relevant phenotypes. Recent studies report fasting plasma levels of erythritol, a commonly used sweetener, are clinically associated with heightened incident CVD risks and enhance thrombosis potential in vitro and in animal models. Effects of dietary erythritol on thrombosis phenotypes in humans have not been examined. Methods: Using a prospective interventional study design (clinicaltrials.gov:NCT04731363), we tested the impact of erythritol or glucose consumption on multiple indices of stimulus-dependent platelet responsiveness in healthy volunteers (n=10 per group). Erythritol plasma levels were quantified with LC-MS/MS. Platelet function at baseline and following erythritol or glucose ingestion was assessed via both aggregometry and analysis of granule markers released. Results: Dietary erythritol (30g), but not glucose (30g), lead to a >1000-fold increase in erythritol plasma concentration (6480[5930-7300]μM versus 3.75[3.35-3.87]μM, P<0.0001) and exhibited acute enhancement of stimulus-dependent aggregation responses in all subjects, agonists and doses examined. Erythritol ingestion also enhanced stimulus-dependent release of the platelet dense granule marker serotonin (P<0.0001 for TRAP6; P=0.004 for ADP) and the platelet alpha granule marker CXCL4 (C-X-C motif ligand-4) (P<0.0001 for TRAP6; P=0.06 for ADP). In contrast, glucose ingestion triggered no significant increases in stimulus-dependent release of either serotonin or CXCL4. Conclusion: Ingestion of a typical quantity of the non-nutritive sweetener erythritol, but not glucose, enhances platelet reactivity in healthy volunteers, raising concerns that erythritol consumption may enhance thrombosis potential. Combined with recent large-scale clinical observational studies and mechanistic cell-based and animal model studies, the present findings suggest that discussion of whether erythritol should be re-evaluated as a food additive with GRAS designation is warranted.