Abstract <p>Gut microbiota is a complex community of microbes that plays a major role in human health and diseases like cancer, diabetes, etc. Gut microbiota normally exists in a symbiotic relationship with the host, while it exerts harmful effects under dysbiotic conditions. Gut microbiota is influenced by a plethora of factors, leading to interindividual variation in its taxonomy and function. Patients respond differently to the same drug, and certain patients experience adverse side effects. Host genetic factors are a major contributor to interindividual variation in drug response, however, recent studies have documented the role of gut microbial enzymes contributing to host drug metabolism. In addition to host metabolizing enzymes, gut microbial enzymes also contribute to drug metabolism. This review highlights the synergistic role of host and gut microbial enzymes in drug metabolism and explores the current approaches to study gut microbial influence progressing towards personalized medicine.</p>