Short-Term Safety of Low-Dose Creatine Hydrochloride: A 28-Day Single-Arm Pilot Study

Background: Creatine monohydrate (typically 5 to 20 g/day) has a well-established safety profile across diverse populations. Creatine hydrochloride (CR-HCl) is a highly soluble creatine formulation that may allow effective supplementation at substantially lower doses (750 mg to 3 g/day); however, controlled human safety data specific to CRHCl remain limited. Objective: To evaluate the short-term laboratory safety and tolerability of low dose CRHCl supplementation administered for 28 days in healthy adults. Methods: This single center, single arm, singl blind pilot safety study enrolled 11 healthy adults (10 females, 1 male; mean age 44.6 plus/minus 7.2 years). Participants consumed 750 mg/day CRHCl for 28 consecutive days while maintaining their usual diet and physical activity patterns. Fasting blood and urine samples were collected at baseline and Day 28. Laboratory assessments included hematological, lipid, and clinical chemistry biomarkers. Pre and post changes were evaluated using paired parametric and nonparametric tests, baseline-adjusted regression models, bootstrap confidence intervals, and false discovery rate (FDR) correction. Results: All participants completed the intervention. No clinically meaningful changes were observed in lipid parameters, hematologic indices, renal markers, or most chemistry analytes after adjustment for multiple comparisons. Fasting glucose increased modestly (8.1 mg/dL) prior to multiplicity adjustment but was not statistically significant after FDR correction and remained within reference ranges. Serum bicarbonate decreased slightly (2.4 mmol/L); although statistically detectable in parametric analysis, values remained within physiological limits and were not consistently supported by nonparametric testing.