Quillaic acid is primarily used in the pharmaceutical industry as a key intermediate in the synthesis of saponins, which are compounds known for their medicinal properties. These saponins are often utilized in the development of vaccines and adjuvants to enhance immune responses. Additionally, quillaic acid is employed in research for studying plant biochemistry and the biosynthesis of triterpenoids. Its role in traditional medicine, particularly in herbal remedies, is also noteworthy, where it contributes to the therapeutic effects of certain plant extracts.