Abstract Molnupiravir (MO) is a pyrimidine nucleoside anti‐SARS‐CoV‐2 drug. MO treatment could cause mild liver injury. However, the underlying mechanism of MO‐induced liver injury and the metabolic pathway of MO in vivo are unclear. In this study, metabolomics analysis and molecular biology methods were used to explore these issues. Through metabolomics analysis, it was found that the homeostasis of pyrimidine, purine, lysophosphatidylcholine (LPC), and amino acids in mice was destroyed after MO treatment. A total of 80 changed metabolites were detected. Among these changed metabolites, 4‐ethylphenyl sulfate, dihydrouracil, and LPC 20:0 was related to the elevation of alkaline phosphatase (ALP), interleukin‐6 (IL6), and nuclear factor kappa‐B (NF‐κB). The levels of 4‐ethylphenyl sulfate, dihydrouracil, and LPC 20:0 in plasma were positively correlated with their levels in the liver, suggesting that these metabolites were associated with MO‐induced liver injury. MO treatment could increase NHC and cytidine levels, activate cytidine deaminase (CDA), and increase LPC levels. CDA and LPC could increase the mRNA expression level of toll‐like receptor (TLR). The current study indicated that the elevation of hepatic TLR may be an important reason for MO leading to the liver injury.

Mass spectrometry‐based metabolomics reveals metabolism of molnupiravir may lead to metabolic disorders and hepatotoxicity