Lactic acid (CAS 50-21-5) is an organic compound formed naturally as an intermediate during anaerobic glycolysis, where sugars are metabolized through fermentation. Biologically, lactic acid reduces local pH environments, thus inhibiting pathogenic microbial growth. Due to this acidifying action, it is utilized in biomedical contexts, including formulations aimed at preventing gastrointestinal microbial fermentation. Additionally, lactic acid served as one of the active ingredients in Phexxi, a non-hormonal contraceptive approved by the FDA in May 2020, wherein it maintains vaginal acidity to exert contraceptive effects.