<p>The current study describes the development, optimization, and assessment of a PHGG based vaginal wash formulation containing lactic acid as the active ingredient for maintaining acidic vaginal pH and supporting beneficial <i>Lactobacillus</i> flora. PHGG was prepared by enzymatic modification in the laboratory, and the formulation was designed using a systematic multi-phase preparation method. Compatibility between lactic acid and formulation excipients was confirmed by FT-IR analysis, which showed retention of characteristic functional group peaks without evidence of chemical interaction. The factors that were sought to be optimized to enhance viscosity and foam stability included the concentration of sodium lauryl ether sulfate and cocamidopropyl betaine using a 3² full factorial experimental design. The quadratic models that were developed with the help of Design-Expert^® software (Version 13.0, Stat-Ease Inc., USA) were statistically significant and showed a high predictive power that showed that the surfactant concentrations had a significant impact on rheological and foaming characteristics. The optimized formulations had a good organoleptic, acidic pH, viscosity and a stable foaming character. Antimicrobial in vitro studies indicated selective antimicrobial effect in <i>Escherichia coli</i> and <i>Candida albicans</i> but not against <i>Lactobacillus acidophilus</i>. The potential of irritation determined using the HET-CAM assay indicated that formulation was not irritant and it was similar to the negative control. The stability studies were performed by short-term stability experiments performed at refrigerated, room temperature and accelerated temperatures and proved that the formulation was physically and functionally stable throughout 6 months.</p> Graphical Abstract <p></p>