Nonsteroidal anti-inflammatory drugs(NSAIDs)are widely used to treat osteoarthritis,rheumatoid arthritis,and acute and chronic painful diseases.Significant interindividual heterogeneity in the efficacy of NSAIDs has been found in patients,which can lead to treatment failure or life-threatening adverse drug reactions.This review will discuss the causes of the variability in the efficacy of NSAIDs in terms of CYP2C9 enzyme gene polymorphism,cyclooxygenase enzyme gene polymorphism,and differences in the intestinal microbiota,to provide a reference for the development of individualized dosing regimens for NSAIDs.